I have a Streaklight 360 TTL which I dearly love and which I use on a modified Stroboframe flash bracket and which I will trigger with a an X-1 radio trigger mounted on either a Canon 6D2 or 7D2. I could,if desired, also trigger this flash with a Canon off camera cord but, prefer to remove the hotshoe mount from the flash and replace it with a 1/4 x 20 screw mount. The flash is quite heavy, especially when it is wearing a modifier, and the screw mount is (IMO) more rugged than the hotshoe mount.
The flash is mounted about six inches above the camera - enough to give a few inches to spare with the X-1 mounted which is why I modified the Stroboflash bracket. I could not use the cameras with the X-1 trigger mounted on an unmodified Stroboframe camera flip bracket since both my 6D2 and 7D2 are equipped with battery packs. The battery pack and X-1 trigger make the cameras too tall to work on the unmodified Stroboframe camera flip bracket...
I have noticed something strange, the trigger will not fire the flash when the flash is directly above the center of the trigger and when the camera is in the landscape position. However the X-1 trigger will fire the flash if the flash is offset about an inch from the center of the trigger.
This doesn't seem to cause any problem since my modified Stroboflash camera flip bracket allows me to move the flash a few inches to either right or left.
However, when the camera is in the portrait position and the X-1 trigger is directly below the center of the flash, the flash will fire from the trigger.
Like I mentioned, my modified Stroboflash camera flip bracket allows me to adjust the position of the flash quite easily - so I have no problem. However, I am wondering about the technical reasons for the flash not firing in the landscape position when it is directly above the trigger. BTW: I have tried firing the hand holding flash in the same relative positions without being mounted on my bracket and the same results occur...
My totally uneducated guess is that the radio signal does not disperse from directly above the X-1 but, does so at a slight angle. Does that sound reasonable to someone more versed in radio signalling than I am.