I had a similar problem yesterday. We have a remote site with 8730 ESS Servers. Our WAN link went down for literally 2 seconds, which was long enough for the ESS to try and take control. Anyway once this lot was sorted out, coverage paths didn't work. If you created a new coverage path it worked, but existing ones didn't.
Here's the crucial bit though!!!
If you do a "ch sys cover" (see below)
The field called "Location for Covered and Forwarded Calls:" this only had a ? in the field. Now a question mark isn't an option, you either have "Called" or "Caller"
I changed this to "Called" and coverage paths seem to work.
It's a weird one, but I reckon nobody will be able to offer an explanation to this one.
CALL COVERAGE/FORWARDING PARAMETERS
Local Cvg Subsequent Redirection/CFWD No Ans Interval (rings): 2
Off-Net Cvg Subsequent Redirection/CFWD No Ans Interval (rings): 2
Coverage - Caller Response Interval (seconds): 4
Threshold for Blocking Off-Net Redirection of Incoming Trunk Calls: 1
Location for Covered and Forwarded Calls: called
COVERAGE
Keep Held SBA at Coverage Point? y
External Coverage Treatment for Transferred Incoming Trunk Calls? n
Immediate Redirection on Receipt of PROGRESS Inband Information? n
Maintain SBA At Principal? y
QSIG VALU Coverage Overrides QSIG Diversion with Rerouting? n
Station Hunt Before Coverage? n
[Started on Version 3 software 15 years a go]