Sorry, I realized the handle shop sign was grabbing the mouse input, even after it became transparent. I've now fixed that behavior and it should work as intended.
The upgraded bomb bag has had a few small fixes:
1. It now gives 1 bomb (as stated), not 2 (old bug).
2. Multiple upgraded bomb bags now do exponential double damage. So 2 upgraded bomb bags should mean every bomb does 4x. 3 means 8x.
I will keep tracking down the performance hiccup bug(s) today and hope to have an update in 24-48 hours at the latest. In the meantime, if you encounter it: after a shop -> save & quit -> restart game -> load save file, and it should reset. This is only a temporary solution, I will keep hunting the root cause.
Thank you!