I noticed that my magic level 1 boots where really low on health (10%) and not automatically repairing. A manual repair command was able to fix them. When asking other players about this issue, they also said its happened with their magic level 1 boots many times too.
They do autorepair when they are about to break. I grinded mine by accident down to near breakage, and then got a chat message stating "autorepair saved my boots from breaking," auto took them off my equip, and put them in my inventory. This was about a week ago, so unless it isn't working at near breakage anymore, they don't repair until almost breaking.
The logic for this seems fine, only guess would be looking at the code that there is a missing case for items to be damaged here maybe, what are you doing?
This might have to do with soul speed and walking on soul soil and soul sand. Just a guess. I could be wrong.
Looks like this is a bug with soul sand damaging boots with soul speed. Added to our development bug tracker.
Soul Speed boots should now correctly auto repair at 50% if damaged on Soul Sand. @ClarinetPhoenix please test these boots on soul sand, as well please do a basic test on any other tool to ensure AutuRepair in general is still working as it should.
Soul Speed Boots(all enchant tiers)s now auto-repairing at 50% dura. Auto-Repair seems to be working correctly and firing at 50% dura, tested on several basic tool types.