It seems to me other FC’s have had to clean up their initialization code to support OneShot, e.g. https://github.com/cleanflight/cleanflight/pull/921 ergo the issue is not with the ESC’s but with FC’s putting out somewhat erratic signals at startup. My guess is that this is what happens here, but without attaching an oscilloscope its hard to be sure.
I had a logic analyser on the outputs and did an entire capture and the signaling seems ok, and yes, I have the same problems 