Off-camera speedlite not synching?!

[SPWP]

Using Canon 7D & 580EX with Phottix Strato wireless remotes (plus Godox AS360 separately). All on manual settings.
Taken light meter reading saying ISO 200 1/250 f4. Fine. 580EX running 1/8.
But when I trigger the flash the camera shows no light received!
I turned the flash DIRECTLY into (just off) the lens and fired - still nothing captured (? should be blown out!).
Got same result when using my spare 40D.
Turn down settings ISO 640 1/1 f4 and I just capture ceiling lights, still no flash (???).
If I remove Phottix and use canon off-camera cable to 580EX I get flash light and when pointed directly at camera I capture flash with light, and slower camera speed gives blow out.
No issue when using the AD360 and it's remote triggers and same power/camera settings.

What the hell's going on with my flash when I'm using the triggers?

Any advice would be really welcomed!

[SPWP]

Well after lots of playing around it turns out that by using the Phottix transmitter off camera (e.g. so I can take self portraits), with receiver #1 cabled to camera's sync port & receiver #2 into the Speedlite, there is an impact on firing.
Looks like flash fires before camera (since I just cannot capture the flash regardless of reducing camera speed).
IF I put transmitter in camera hotshoe (so just have 580EX receiving) flash fires perfectly and blows image.

Guess I'll have to rethink the off-camera triggering