I wanted to get an update / link to fix on the following issue labeled as 'active' on the Wiki (my apologies is this was somehow fixed and discussed in the posts, I didn't do an exhaustive search - but I still have problems with it):

Backtest broken with Index Out Of Range message with enabled Benchmark Buy&Hold and a DataSet symbol doesn't contain dates within backtest range
Synchronization issue: enabled Benchmark Buy&Hold symbol breaks a multi-symbol backtest and generates an "Index Out Of Range" exception when backtested DataSet contains a symbol whose starting date doesn't fall in selected data loading range.

Thanks,

It's a live bug recently discovered in 6.2 and existing on the Open Issues page.

P.S. In other words, when it disappears from that list it's fixed, otherwise the issue remains.