If it's not picking it up possibly the custommix file is corrupted
This is an example of a custommix adding IPTV streams to HD channels using Sky UK SD region not HD or custom
I've only edited most used entertainment channels, all movies and most sport
Change the .ts links and service types
Just add the stream to the hd number and remove the delete if you want to add more
This is for stream relay if you don't use that
Delete lines 158 to 199