In my skills list, I can see that I have 13 learners assigned to a skill. When I select the option to Assign to Learners, only 1 user group is viewable (the user group only has 4 people assigned to it). How can I view the other 9 people assigned? How can I remove a learner from a skill?
Could you please check if you see all the 13 users available when you go to the Users ->User Groups->Custom Groups?
Also, are they(rest 9 users) available in Learners tab ?
There a two ways the no of leaner count increases under Skills tab. Once way is if you assign that Skill to course (while creating the course as an Author) and then you enroll some learners to that course. Other way is that you can go to Skill Tab and assign learners manually (Only Users Group). Only learners that are added from skills tab will be visible there.
So I believe that you added a user group to that Skill which contains 4 users hence they are visible. The rest 9 are the one's that were enrolled to a course containing that Skill hence they are not visible.