hey sorry, yes i did solved it in the end, sorry for the late reply.
basically it all depends how you orient your joints/Bones in the DCC progam.
I used blender, i had a huge problem with that, but i manage to create a small script that orients my bones in a coplanar way. after that i export the rig and imported it in UE and everything worked perfectly, it seems that blender had some problems how it calculates the bones orientation of a 3 bones chain, like an arm or a leg, anyway, thank you for your help.
sorry for this late reply.
for everyone having the same problem, this is the script i used, it is in italian, but i hope you can make it through anyway.
thanks.
Orienter_Coplanar_V4.zip (5.0 KB)
this is an addon for blender, it has a little and really simple UI with 3 text boxes and a button. if you are stuck and for some reason it is not working, check out the blender console, there are prints that explain why is not working. it is still in italian, so you might want to translate that.
thank you for your help