Bulk Rename Utility

I'm using BRU 3.4.4.0 in Windows 10 to append a timestamp string onto my existing filename, using the Date Modified as the source and Auto Date to format it. My custom string is _%Y%m%d_%H%M%S and the resulting filename is TC020001_20230415_020100.AVI My difficulty, and I assume I'm doing something wrong here, is that the Date Modified I started with was 14/04/2021 22:01:00. So the day has been incremented by one and the hour by four.

I've looked and looked, and can't see what I'm doing wrong. Can anybody help me? Thanks.

Sorry, what I left out was that the timestamp string I wanted generated was in the format _YYYYMMDD_HHMMSS. The format coming out is correct, but some of the DD and HH figures aren't.

Another mistake: Date Modified was 14/04/2023 not 2021!