UE4 crashs when i rename material function category

Hello Guys, the Unreals crashs on my face when i renames any material Function category,i tried a lot of diferent options, but its only possible to save materials functions on Misc category inside my Unreal project :confused:

This is a well known bug in 4.12, which should be fixed in 4.13 when it releases.
works fine in 4.11 though.