Errors when using TestCoverage, 'Somebody else is using the Monitor'

When running the command 

do ##class(TestCoverage.Manager).RunTest(,"/nodelete",.userParams)

I now get the following error. these tests used to run fine.

LogStateStatus:0:TestCoverage.Manager:OnBeforeAllTests:ERROR #6060: Somebody else is using the Monitor. <<==== **FAILED**

Can someone please point me in the right direction?