I'm pretty sure my combat log usually specifies that it's an opportunity attack. I'll have to make sure I check when it happens again.
This is my take on what I think happens.
There are two bugs in play here.
1. When you use ghost man pathing(any action that requires moving and shows a silhouette where the action will take place,) if you are attacked by an attack of opportunity, your character will be halted and your action consumed. No action will have been taken, but the game thinks it was.
2. When you use ghost man pathing to attack, your character moves to the target within their reach. Your character then repositions themselves for the attack, but moves out of reach ever so slightly and triggers an attack of opportunity, even though it is not intended. Once you are attacked, the bug from point 1 takes place and you no longer have an action to make the attack that never went off.