Rated 5 out of 5 stars

It works !!! Just download v1.2.0pre3 and install manually.
https://github.com/Ximi1970/Manually-Sort-Folders/releases/download/v1.2.0pre3/manually_sort_folders-1.2.0pre3.xpi

This review is for a previous version of the add-on (1.1.1).  This user has a previous review of this add-on.