Yeah, we found two specific issues
- He wasn't able to install/update mods because all the *.sixmirror.com hosts were blocked by a security software. The only outward sign of this was a "Host list exhausted" message, but thankfully the logs contained the actual hosts it was trying to access and trying to access them through his browser gave a nice "This website contains potentially spooky stuff, so we blocked it" screen.
- All his local mods weren't recognized, showing as "local mod, 0KB". No error messages in the GUI, but the error log contained a reference to "CRITICAL: The mod token existed but was not attached to a mod", so we deleted the .snyq folder and all .synqinfo files inside the modfolders (use search, don't try and delete each one manually^^)
Before I actually found those two issues we also did the usual "delete EVERYTHING related to play with six" thing, very very thoroughly, but in the end I think the errors weren't actually related to the program itself but to firewall/security and corrupted .synqinfo files