FWIW, channel Numbers and grouping from MythTV backend does not seem to be working on Kodi 17 Android but is working on Kodi 17 Ubuntu Linux install.
I have several Android boxes showing the same issue and several linux boxes that are just fine.
I’ve made sure that the settings are the same on both boxes.
I have two HD Homeruns feeding the MythTV backend.
Note: I fixed my problem by wiping the Android installation and setting Use Channel Numbers from backend before enabling mythtv pvr client.
I suspect the problem is that Android Kodi does not properly clear it’s settings and data when the channel groupings and numbers are changed.