Not sure what caused it, and the bug is not effecting all my tools (3/4) but I came back to town to replace tools and noticed only my axe had durability loss from use.
I have and indestructible affix on my gloves paired with can’t be repaired that I rolled while equipped on my character. Again no clue if this could have caused it.
relaunching the game has somehow magically fixed it? tools are breaking again 
Update. It’s still happening randomly (infinite durability) but I’m not playing the game and differently to pre breach and didn’t noticed it start until I rolled my first pair of unbreakable gloves so I’m willing to bet something under the hood could be related and impacting the tools.