im going to chime in here because I originally had the BT box Pro (back in the days it was BT doing the TV).
I encountered similar with my sony. - for me it was a case of diabling every enhancement the TV has, including 'filmmaker' mode. (sony calls it something else), setting the correct HDMI port and for frame rate matching, I actually set it on the TV itself. I put it in as 'always'
The behaviour I would get was this...
box on main menu, switch to BT Sports Ultimate HDR (as it was known then!), the channel would load, then my screen would go black, then come back on, with a delay of 3 secconds for my AVR to lock to the audio and start outputting. result was no Judder. whilst here my TV would engage HDR 10 as requested. for all other channels would just output HD. and were fine.
Perhaps look deep into the TV settings, frame rate matching may well be there.
to clarify, I have returned from the darkside, like skywalker has shown me the way of the force and I am once again with BT (EE as it is now) with an Apple TV 4k. This is set to frame rate match as well as my TV and they both work in tandem and no judder at all. The oddball (and people see it as a feature - I can't fathom why), is Apple wants you to pick 4K HDR or 4K Dolby Vision but that forces everything under the golden sun to be in Dolby Vision or HDR. This makes TNT Ultimate washed out. so the magic sauce for apple is to pop the box into 4K SDR mode, set it to 4:4:4, and if you have an iphone, run the calibration. Then set frame rate / range matching both ON, and those apps like Netflix, apple TV, amazon... will switch modes as required.
My gripe (and it's just me being picky and not EE's fault) - is there is no way to upgrade HBO max, considering my TNT sub is tied here as well.
on the subject of TNT sports ultimate, is the HDR version only on the pro box?
