How are you triggering your Rovel with your mitros+ in HSS
Hi, A Mitros + 'Plus' works just like an Odin TCU to provide the early 'HSS like' trigger signal. I use a Strato II Rx wired to my Jinbei/Rovelight with the latter providing long duration flashes when set to 'H'. (You could use an Odin Rx unit but it costs more unless you already have a spare.)
Image with Strato II:
The Mitros + must have HSS showing on its screen and Channel & Group must be set appropriately.
This is 'Supersync' so there is a gradient across the frame - with Canon, that's darker at the top (landscape) as the image is normally viewed. There are techniques at the shooting stage which somewhat ameliorate the visibility of the gradient.