I have a work around for this coming. This is to make your
uncategorised thumbnail show. Tested it on my own profile.
https://www.imagefap.com/profile/longhairfish/galleries1. You will have to move all of your uncategorised galleries to a new folder. My Fap - My Content - Add New Folder. Give the folder a name.
2. Then click the + next to uncategorised folder. Click the top box so all of your galleries are selected
except for one gallery.
3. At the top right you see Bulk Actions. You will "Move To" the folder you just created.
Now you have just one gallery in uncategorised.
Give the site about 30 minutes to index your profile. Maybe a little longer.
If by chance that does not work, delete the final gallery as mentioned in step 2. Again, wait a while for the site to organize your stuff.
Many users, including myself don't always sort their galleries in to folders. After a while the uncategorised gets so full and 'confused' with gallery deletions and additions it finally gives up.
Keeping your galleries sorted may solve this problem.