Importing giving errors, where before it didnt

Hello, i have been working on a game, and im having a problem that right now has completely stoped me form progressing.
i need to fix this ASAP. The problem is:

when i import my FBX files with animations into unity, they seem to be losing the root motion, instead of moving the feets and the torso when walkiing, the torso is fixed and every thing else moves around, making all the animations horribly wrong, and losing the world positions for animations with more than one actor.

I traced the problem and it is a unity problem, after many tries , i ended up, importing again a file that already was in the project and was working before. this file Anim03, works perfectly. but now i reimported it under another name, they are using the same settings, and even copying from the same avatar, but im getting thsi error. any idea how ot fix this?

this is the only clue that i have to what may cause animations to dont work properly, but it may not even be that.