Godox flash - syncro problem

[bronstaf]

I have an X-T2 and a Godox 860. I have set the flash as a slave to the remote control connected to the camera. I am using the flash in manual mode through channel B.
I am taking still life photos with iso 200, f stop 5.6 and speed 60.
This is my problem.
Sometimes the remote control fires the flash and sometimes it doesn't. There doesn't seem to be a pattern. Although when the camera goes into "standby" it seems to also put the remote control into "standby". But the camera doesn't have to be on hold for this to happen.
I've tried changing the card, turning the camera on and off, selecting the channel on the remote, and testing the flash. Testing the flash shows me that the remote control and the flash are connected. Is there something in the camera settings that I should learn about? Is it, in fact, a problem with the camera or the flash?
Although I am new to flash photography, I am working on this with my photography teacher (who is a professional photographer) and she is just as confused as I am.
I would appreciate any advice that resolves this. Thanks in advance.

Edited November 27, 2020 by bronstaf
wrong technical info