Windows 10 updates also jumped in there, disallowing changes as it is your users folder. Epsecially the standrd windows tool Defender acted like a real protector in the past already.
So make sure the whitelist allows changes to the addons and savedvariables folders.
And I also remember someone having problems with other installed software, no antirvirus or similar, but it was something else.
Did a search for it but wasn't able to find it anymore so far
