I noticed today after I updated AssistUO  that where my skills are normally listed, it was completely empty. I've heard other players were having the same trouble so I played around with it for a bit. Good news! No need to page staff, as there is a simple fix to it. Down at the bottom of your skills page there is a tab that is labeled New Group. Go ahead and click on that once and you will notice all of your skills are now listed under the 'New Group' you just created. Now you are free to create as many groups as needed to organize your skills to your preference.
 
For example: Lets say I want 5 groups...one for Combat, one for Magic, one for Crafting, one for Barding, and one for Misc Skills. After creating the initial group to get my skills to show up, I renamed that group to Combat, then I clicked on the New Group tab four more times in order to create the others. If you are unsure on how to rename the group, all you have to do is click on the group title once..delete the 'New Group' text..and type in your desired group name.
Hope that helps!
 
P.S. Make sure you log out of UO, close it completely, reopen, and log back into UO in order for the changes to save.