Usually I use fbx units scale but had to use all local this time(to match the 100 armature scale in unity) then used Pumkins tools to copy everything from the original(even though it no longer shows up it works) and click the revert scale in pumkins after the transfer. Sometimes it works with no issues other times addons etc will be messed up.. Honestly exporting fbx files seems kinda janky...something to do with the python script.

Also if you ever have the issue of the body crumpling up you can usally set the armature type to none then back to humanoid to fix it(make sure the check chest and jaw bones after the switch).

Glad i could help you out, if theres any issues at all dont hesitiate to mention them.