When a character is copied, the selected feats of the original character are not set in the copy.

Steps to reproduce:

1. Create a character at least at level 4 and make sure feats are enabled for that character.
2. Select any feat for the characters level 4 ability score improvement.
3. Copy the character.
4. Check if the copy has the same or any feat selected as their level 4 ability score improvement.

Just did it on a test character.

Feat copied fine.

Are you possibly copying a character in a shared campaign with sources you don't have access to?  If you do that the copy is not considered in the campaign and will only have access to what you have access to.

The bug (as discussed in this thread) isn't that the feats don't copy over - it's that in the builder the ASI highlights blue and shows as unchosen as if it didn't copy over (when it actually did). It's just a display issue.