Since recently getting my 1DX, I've been testing out everything. I was playing around with the 580EX II on-camera, and everything looked good. I went into my studio and fired up my strobes. Each one has a PW II on it. I put the MiniTT1 on the 1DX hotshoe, hit the test button (fired all the strobes) and then tried to take a picture...nothing (triggered). Tried again, nothing. Tried the test button again, took the Mini off and put it back on again, fired the strobes. Tried again, nothing. After that, it was about half the time that it triggered the strobes. Removed the Mini and tried the FlexTT5. Similar results, but the strobes triggered about 2/3 of the time. Removed the FlexTT5 and tried a plain ol' PW II, and the strobes fired every time. I don't remember reading about anything peculiar with the 1DX hotshoe and was wondering if anyone else has had problems like this. I haven't updated the firmware in either of these for quite a while, but I doubt that would cause anything like this. I'll try fresh batteries, but it hasn't been long since I put fresh batteries in both of these. I guess the other possibility is that the contacts are not lining up just right.