What is meant by "rounding"?
These are historical M1 data with exact timestamps, already rounded to a whole minute.
Anyway, it has to be verified and confirmed that the first bar of the week starts on time and is of duration specified by BarPeriod/BarOffset.

Quote:
O-H-L-C, all the same, is normal and not a bug.
Sure. I did not imply it is.

The bug is that a bar is not constructed/is skipped, despite data exist in a database.

Please have a look at the screenshot.