Tvheadend

I'm trying to use a custom "MPEG-TS Spawn" stream profile with some DVB-S(2) channels using the latest build of Tvheadend (4.3-1312~ge38a877) on Ubuntu 16.04 LTS but no clients are able to playback the streams. TVHClient and Kodi can't even see the profile at all. Dream Player says "Video cannot be played" with no other useful info except "MP State: 6". There are no errors or warnings in the Tvheadend log.

Any ideas? Do these clients just not support certain stream profiles? If so, what does everyone use for this feature?