Tvheadend

Okay so I am a newbie and I have google around for answers to my question but have not found anything really good so figured I would ask all you experts

I use iptveditor to maintain my playlists... eg ..filter out channels I dont want and organize my groups. I also assign epg sources to the channels there. Makes it easier to maintain what I want. In iptveditor 99% of my channels have an epg source assigned.

I use webgrabber to pipe my epg data from iptveditor to the external xmltv module (socks). In which I see in the log
2021-01-21 15:45:08.001 epgdb: snapshot start
2021-01-21 15:45:08.152 epgdb: queued to save (size 18724804)
2021-01-21 15:45:08.152 epgdb: brands 0
2021-01-21 15:45:08.152 epgdb: seasons 0
2021-01-21 15:45:08.152 epgdb: episodes 34534
2021-01-21 15:45:08.152 epgdb: broadcasts 34534
2021-01-21 15:45:08.153 epgdb: save start
2021-01-21 15:45:08.157 epgdb: stored (size 18724804)

When I look at my channels a decent amount of them show no epg source(roughly 60%). I can manually add them to the channel so I know the data imported but my ask is why is not auto adding them? Can someone explain to me how tvheadend decides epg source and also if someone has any ideas how I can correct this because I hate to have to manually map 1500 channels in tvheadend.

If I need to supply more info to help get a good answer let me know..

Appreciate any help and thanks!!!!