BiaBman, we are just trying to help!
Are you working in 2/4 time? I just ran some experiments and in 4/4 and 3/4 time the copy and paste works perfectly. But in 2/4/ time it doesn't work at all. In 2/4 time you must use the copy and paste method that is in the microchord window: see attached pic. You may have in fact found a bug.
Thanks Mario.
I know you are just trying to help.
And I am not trying to make any trouble.

The song is in 4/4 time. I just tried it in 3/4 and it didn't work there either.
I'm using BIAB fresh out of the box. Straight, vanilla BIAB.
Starting a fresh song with three bars.