I would recommend checking if there are any hung processes in a ""stopping"" state in the control room for the particular runtime resource your experiencing issues with. If you have processes that are in a stopping state, it will need to be cleared by running the following query against your Blue Prism database:
declare @now datetime
set @now = getdate()
update bpasession set enddatetime = @now, stoprequested = null, statusid= 3 where sessionnumber = Session_Number_From_Blue_Prism