Since the in-game bug report functionality does not appear to work at the moment, I am instead posting the bug report here. Please let me know in case there's any alternative location I can use to report issues like this and I'll be happy to report this there again.

When using the Masterkey underbarrel shotgun upgrade and trying to reload on a full magazine, the beginning and end of the reload animation will be played, but no shells will be inserted into the magazine. Even though this behavior might be intentional, it seems odd when compared to reloads on a full magazine with primary and secondary weapons.

Steps to reproduce:

  1. Equip any weapon which can fit the Masterkey underbarrel shotgun (in my particular case, I used the M4A1).
  2. Add the Masterkey underbarrel shotgun.
  3. (if necessary) Resupply.
  4. Reload once to fill up the magazine.
  5. Reload again.
  6. Notice that the beginning of the reload animation starts playing (gun is moved upward) and immediately proceeds to the end of the animation (gun is moved downward).