Strange bug with an ammo machine

Playing a MP game with my son, him as host.
Just progressed story to the first Guardian, and returned to Sanctuary III.

Went to the Ammo vending machine, offered $75 to top up your ammo… So pressed Triangle (ps4) I got no ammo, but lost the money.

I was then able to repeat this multiple times, effectively spending cash on nothing.

Not a game breaker or a big issue, but a bug none-the-less