I've had lots of problems with Speedlite triggers on my 5D Mk4, but when I put the same trigger on my 5D Mk3 or 7D Mk2 everything works fine.
It's definitely not an issue with RF channel (frequency) settings or interference, because the other cameras trigger flawlessly in the same environment. It's something with the 5D Mk4 that's different.
I know it's not the 5D Mk4 hotshoe, because an on-camera Speedlite works just fine, and so do my Paul C Buff triggers for my Einsteins.
The problem happens with all three of these radio triggers:
ORLIT TR-611C (transceiver): https://www.adorama.com/orrrtr611c.html
ORLIT ST-RT (similar to the Canon ST-E3-RT): https://www.adorama.com/orrrstrt.html
When I use any of the above triggers with the 5D Mk4, it seems to trigger only every other time, and sometimes not even that. After the two ORLIT triggers failed me repeatedly, I purchased the Canon ST-E3-RT a month ago, hoping that it would be more reliable, but it failed completely on me last week. I also brought my 7D Mk2 along, and had to switch cameras to complete my shoot!
Oddly enough, the only consistent Speedlite triggering I can get with the 5D Mk4 is with the Yongnuo system. When I use the Yongnuo YN622C-TX transmitter and Younguo YN-622C receivers, it works every time!
Am I the only one this is happening to? Is there a setting or something that I'm just missing?