A new subdirectory of APPDATA\Mozilla\SystemExtensionsDev which causes the Mozilla directory to be left and a new Mozilla directory at LOCALLOW\Mozilla. Both directories are empty. This will be addressed in the next release.
You can test the upcoming version of the launcher here: Firefox Portable Launcher 2.1.1.
MD5: 73aa27297d170a8415f9025d5a8785c7
UPDATED: 2017-12-21 - Added fix for updates empty directories.
I added in a fix for the Mozilla updates directories that the Firefox update checker is mistakenly creating.
Sometimes, the impossible can become possible, if you're awesome!
This is fixed in the just released Firefox Portable 57.0.3 and will be fixed shortly in the upcoming 52.5.3 ESR release (currently mirroring to our download servers). The Beta, Developer, and Nightly channels will also receive the fix in their regularly scheduled releases.
Sometimes, the impossible can become possible, if you're awesome!