The data range setting is no longer operation correctly.
Any attempts to enter a date earlier than the current date (i.e. 12/27/18) is ignored and the listing reverts back to the current date.

To start with,

1. What tool are you using? (Strategy Window, Strategy Monitor)
2. What are the start / end dates (exactly)?

And to clarify explanation you might want to send a screen shot by striking the "Prt Scr" key and pasting into Paint or other imaging application (with Ctrl-V or Shift-Ins). Save as PNG and attach using "Add attachments" when replying.

Strategy monitor - see dates on images attached

In the Preferences dialog (F12 key) > Advanced Options, how is the "Data range" checkbox configured?

unchecked
checking this box does not correct the problem

I think the reason is that the Strategy window is not in focus. In WL it's possible to make changes to that dropdown when other tool is in focus, return, and notice that the changes aren't applied.

On "WLP Image to today.png" it's clearly seen that the Strategy is maximized (i.e. no chance to take it out of focus). Here, any changes you make to the dropdown box will be applied.

What's different on the other screenshot is that Wealth-Lab's title bar no longer indicates strategy name and DataSet symbols. Probably the Trade Tool has focus. So when you bring back the strategy to focus you notice that no changes to the dropdown box are being applied.

Bottom line: maximize the Strategy window or Ctrl-T to hide 'Trade Ticket'.

None of these fixes solve the problem. Up until about 1/9/18 I have been able to change data range without difficulty for more years than I can remember. The problem appears to be systemic, I have WL 6.9.17 installed on three systems and the problems persist across all three. There has to be a broader issue here.

btw, WLP 6.9.17 is an oudated build.

Nobody else has reported this issue before but you. Obviously, it's specific to your computer configuration. Considering that you have the skills to develop custom DLLs, this gives you a greater degree of freedom to shoot yourself in the foot! ;)

So if I were in your position I'd ask myself:

1. What did I do on my PCs around 1/9/18 to cause this? (Remember that WLP hasn't changed for years now.)
2. How do I configure my workflow? Is there anything specific to my workflow that the technician may have no slightest idea of?
3. For example, have I made any changes to the WealthLabPro folder under my %AppData% like making WealthLabConfig.txt read-only or the like?
4. How many strategies are affected: all, certain ones, or just one?
5. What about the other dropdown boxes: position size, scale: do they also lose their entered value?
6. Can I walk the technician through to reproduce the issue step by step?

I have voiced the two potential 'generic' reasons i.e. a) saving Data Range and b) window out of focus. I cannot be sure if you followed my directions correctly so the more details the greater the chance of resolution.

After upgrading to WLP 6.9.19, the first thing I'd do is work through the blurry fonts work around so that the controls are displayed properly in WLP. It's pretty suspicious that your Date Control dialog is displayed in the middle of the screen instead of next to the dropdown control.

Although it doesn't seem to be the case here (after running a backtest on a DataSet), when Streaming is selected the "to" date is locked to "Current", which disables that selection.

If 6.9.17 is out of date why does the app tell me its its to date?
Last strategy update was 3/11/17.
Last event (on or about 1/9/19) was a ATP update which caused the application to lockup. Had to remove additional procedures in the update, which affected data feed and multi monitor (3) display.
Cannot correct fonts focus because of multiple display size requirements.
There have been no changes in the workflow.
I will delete and download WL again, hopefully with 6.9.29 on board.
In the meantime, please review WLP Exhibit 1. This was an attempt to workaround the problem by initially backtesting to an earlier date. Note the difference between the actual and requested Range.

QUOTE:
Any attempts to enter a date earlier than the current date (i.e. 12/27/18) is ignored and the listing reverts back to the current date.

Back to post #1. What is that "listing" that reverts back? Wanted to ask this on day one. I'm not convinced there's a bug here. What happens exactly, step by step? And how do you expect WLP to perform in this context? In greater detail please.

QUOTE:
Note the difference between the actual and requested Range.

Not seening any issue here. 12/1 and 12/2 were Saturday and Sunday.

P.S.

QUOTE:
Cannot correct fonts focus because of multiple display size requirements.

So the centered Data Range control's position is caused by your multi-monitor setup?

QUOTE:
Note the difference between the actual and requested Range.

The "Range" shown in the Performance report shows the date of the latest bar loaded in the backtest: 11/30/2018. You requested 12/2/2018, but as Eugene pointed out, 12/1 and 12/2 fall on a weekend, so the result is precisely what we expect to see.

Re #11 quote;
The "listing" is the backtest result (i.e. WLP Image -today .pmg) which is a listing of all the symbols in the dataset sorted by symbol to the end date specified on the drop down range.
The values in the listing by symbol did not change between the "to-day" and the "past" listings.

Re#12 Multi Monitor setup
Yes Matrox PowerDesk specifies the pontrol position as "centered"

Re #8. #9 Build
Today's download (from Fidelity.com) still specifies WL as Version 6.9.17.0 Build 7 not 6.9.19

New attachments were run after a new download and are behaving as expected.

See new attachments

So it works again now? As you know, changing the data range (or position size for this matter) does not trigger a recalculation of the backtest performance if it's a multi-symbol portfolio backtest (as opposed to single symbol mode). Are you sure you actually reran the MSB backtest when you were experiencing the issue before?

Nothing has changed in the procedures or data (other than updating symbols in the data-set) for years. I can only assume a data glitch or corruption between updates.