I'll share my config settings that might be relevant and you could check whether yours differ in any way and try setting them the same as mine to see if it helps.
TV Server Config:
General: Delay in seconds before TVServer detects cards - 30
Plugins - Power Scheduler - Advanced: Reinitialize service on wakeup
Media Portal Config:
General:
Allow S3 Standby
Restart MediaPortal on resume
Can't think of any others that would make any difference so if those don't help, sorry!