In rare cases the items are unfortunately destroyed.

Version: ItemsDontBreak-1.17.1-0.4.0

Do you happen to remember which cases? I can look into it but I don't know if I'll be able to fix them.

Unfortunately no.

have you already found something?

I could never figure out what could cause it. It was reliable in my development environment testing.

Err premature send.
Was going to say that my only guess is some interaction with another mod is causing the logic not to take effect.

It does not always happen. Do you have all the enchantments on the tools, including the beacon?

Happens to me also, when I'm mining using a beacon.
I suppose the reason is that force break is triggered by sprinting and I do sprint when mining using a beacon.
I'm going to look into the source code right now and maybe push a fix.