Selecting new weapon attachments during the same match you unlock them

I've noticed an issue with selecting newly unlocked attachments on weapons during the same match I unlocked them. If I click on them to equip them, even though I have more than enough points, it will immediately return to what was previously equipped. However I also was able to confirm that attachments previously unlocked, i.e. the ones you start with like sights, could be changed mid-match.

I don't know if this is a bug or an intended feature, but the former feels more likely since it doesn't outright confirm I shouldn't be able to equip these new attachments. I am able to finally attach the new ones in the next match though - so its not a major game breaking bug, but it is annoying.

Apologies if this is already known, I haven't been able to find any existing posts noting this.