I have two Windows 10 PCs (creators update, fully patched) and, having installed Kodi 17.3 (which includes v 3.4.5 of the Addon), I see the 'PVR manager starting up / Loading channels from clients' information message but no channels are loaded and the message eventually blinks off.
I fixed the problem with the 'Clear data' option under PVR & Live TV settings in Kodi.
It seems that something is trying to add duplicate channels to the database creating constraint violations.
Just thought I'd post in case anyone else encounters the same problem.
Andy