So, to get on the same page. You are using a Skill Expression Group to assign members to the group. Yes, that scrolling does have some issues, especially if you have a larger number of members (over 100). Also, it is looking dynamically at all the users in your system for the skill and skill level so that can take time and requires updating. If you have a small number (less than 100), that list is being updated more frequently and can cause the behavior you are experiencing. Genesys is working on this and the Queue membership anomalies when using Skill Expression Groups.