1 - Export your http://DVRIP:8089/devices/ANY/channels.m3u?codec=copy&format=ts to local M3U file or create one manually to test it out (I’ve used Feedlix to extract the M3U file and there are other ways to do this, search the forum)
2 - Use a Text editor program and edit the local M3U file and add these dummy duplicate channels, sample below (the bug was when you have duplicate channels inside the local M3U file, the iProTV get into a loop when you created a grouped view that have the duplicate channels selected in the multi-view mode, so the more duplicate channels you create in the local M3U file the more multi-view screens you get)
#EXTM3U
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV1
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV2
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV3
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV4
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV5
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV6
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV7
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV8
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="1.0" tvg-id="1.0" tvg-chno="1.0" tvg-logo="" tvc-guide-stationid="" tvg-name="" group-title="Multiview",MV9
http://DVRIP:8089/devices/ANY/channels/1.0/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="2.1" tvg-id="2.1" tvg-chno="2.1" tvg-logo="https://tmsimg.fancybits.co/assets/s32356_h3_ba.png?w=360&h=270" tvc-guide-stationid="21634" tvg-name="PBS" group-title="Favorites",PBS
http://DVRIP:8089/devices/ANY/channels/2.1/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="4.1" tvg-id="4.1" tvg-chno="4.1" tvg-logo="https://tmsimg.fancybits.co/assets/s28711_ll_h15_ab.png?w=360&h=270" tvc-guide-stationid="21234" tvg-name="CBS" group-title="Favorites",CBS
http://DVRIP:8089/devices/ANY/channels/4.1/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="5.1" tvg-id="5.1" tvg-chno="5.1" tvg-logo="https://tmsimg.fancybits.co/assets/s28708_ll_h15_ac.png?w=360&h=270" tvc-guide-stationid="21236" tvg-name="ABC" group-title="Favorites",ABC
http://DVRIP:8089/devices/ANY/channels/5.1/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="9.1" tvg-id="9.1" tvg-chno="9.1" tvg-logo="https://tmsimg.fancybits.co/assets/s28719_h3_ba.png?w=360&h=270" tvc-guide-stationid="24504" tvg-name="FOX" group-title="Favorites",FOX
http://DVRIP:8089/devices/ANY/channels/9.1/stream.mpg?codec=copy&format=ts
#EXTINF:-1 channel-id="11.1" tvg-id="11.1" tvg-chno="11.1" tvg-logo="https://tmsimg.fancybits.co/assets/s28717_ll_h15_ac.png?w=360&h=270" tvc-guide-stationid="20505" tvg-name="NBC" group-title="Favorites",NBC
http://DVRIP:8089/devices/ANY/channels/11.1/stream.mpg?codec=copy&format=ts
3 - Upload the edited local M3U file to Google Drive and create a Google Drive direct link for your M3U file (Google Drive Direct Link Generator) - this step you need to host your own M3U file publicly so iProTV can get to it because iProTV doesn’t support local M3U file yet.
4 - Go to iProTV and Add Provider and select Remote File m3u and point to the Google Drive direct link you’ve just created in step 3.
5 - Open one of the dummy channel and go into multi-view mode and add another dummy channel and now save the grouped views name as whatever you want or call it Template so you can reuse it to create other views later.
6 - When you open the new grouped view you can see it’ll open a bunch for dummy channels in multi-view mode. At this point you can replace the dummy channels with the real channels and save the grouped view with another name.
I created a template view for like 8 channels and use that as my starting point. You can create as many as you want, I think the latest Apple TV 4K can handles up to 16+ screens with h264 but iProTV layout you get 2 large split screen on top and it will add the rest of the channels to bottom of the view.
Once you created the multi-view template you can delete the dummy channels, if you don’t want to see them from your Google Drive hosted remote M3U file and make sure to refresh the Provider in settings for the changes to take effect.