i also have this problem. last working version for me was mp2 spring 2016 release. i use win 8.1 x64, kodi and mp tv server on the same pc. the behavior is strange: after i turn on pc or after a windows-reboot pvr manager doesnt start:
13:38:22.149 T:2732 INFO: AddOnLog: MediaPortal PVR Client: Mediaportal pvr addon 2.4.19 connecting to 127.0.0.1:9596
13:38:22.149 T:2732 DEBUG: AddOnLog: MediaPortal PVR Client: Connection state change (0 -> 7)
13:38:22.149 T:2732 DEBUG: AddOnLog: MediaPortal PVR Client: GetConnectionString:
13:38:22.149 T:2732 DEBUG: PVR - V1::KodiAPI:
VR::CAddonCallbacksPVR:
VRConnectionStateChange - state for connection '' on client 'MediaPortal PVR Client' changed from '0' to '7'
13:38:22.149 T:2744 ERROR: PVR - PVR::CPVRClients::ConnectionStateChange - invalid handler data
if i close kodi (back to desktop) and start kodi again, pvr is working perfectly fine:
13:42:33.336 T:3884 INFO: AddOnLog: MediaPortal PVR Client: Mediaportal pvr addon 2.4.19 connecting to 127.0.0.1:9596
13:42:33.336 T:3884 DEBUG: AddOnLog: MediaPortal PVR Client: Connection state change (0 -> 7)
13:42:33.336 T:3884 DEBUG: AddOnLog: MediaPortal PVR Client: GetConnectionString:
13:42:33.336 T:3884 DEBUG: PVR - V1::KodiAPI:
VR::CAddonCallbacksPVR:
VRConnectionStateChange - state for connection '' on client 'MediaPortal PVR Client' changed from '0' to '7'
13:42:33.336 T:3884 INFO: AddOnLog: MediaPortal PVR Client: Connected to 127.0.0.1:9596
(pvr is also working fine afer start/restart windows and than open/close the mp2 tvserver configuration setup bevor starting kodi).