Symptoms
Customer tried to remove a Lync call group in hosting control panel and got endless Loading...
icon after deleting a call group.
Cause
The issue has been reported to the development team as APS-16764 and fixed in OA 5.5 update 7 https://kb.cloudblue.com/en/122744
Resolution
Please install OA 5.5 update 7 to fix the issue.