I noticed that if you load a crossbow and fire it immediately after having loaded it, the arrow will not be fired but the crossbow will still be unloaded.
It is a small bug, because if you wait for a second before firing or release the right mouse button and walk before firing, the arrow will still be fired.
It is only when you try to load the crossbow and immediately after it is loaded, fire the crossbow that this will occur.
Can't reproduce in 1.16.2 pre 2 - shot as fast as i could successfully