Getting Error when Proxy enters Absence

Summary:

We had a need for Staff Assistants to be able to Add Absences on their leader's record. Delegation does not work since it only gives access to the leader's employees, not the leader's record. We found the Proxy access and have set that up, but we are now getting an error when an employee logs in and switches to the profile of another person. When they go to Add Absence and Submit, they get this error message?

You can't process this absence as another absence is currently being processed. Try again later.

I've confirmed there is no other absence outstanding for the person, accruals aren't being run, etc.