Btw did you setup the ‘DefaultGroup’/‘TheAnimSlot’ AnimGroup/AnimSlot combo on your weapon (all FPV weapons need to have it), and set your FPV Weapon Anim Montages to play on the ‘TheAnimSlot’ Slot?
That won’t explain why your Anim Sequences aren’t playing, but it’s important anyway in order for the Anim Montages to play 
Cheers,