Yesterday, I experienced a bug like this while spectating my friends’ games in real-time.
When I inadvertently clicked on the unit icon placed in the friend’s production queue, the unit was deleted from the queue.
When I clicked it one more time, it was deleted as expected.
It was the last game of yesterday, so we couldn’t check further. It was not possible to determine whether it was a bug that was activated unconditionally or under certain conditions.
If anyone can check it, please check it. This is not a ‘replay’, but a ‘real-time spectating’.
To explain a bit more additional situations,
The map was “Arabia” and the civilization was England vs. AD.