I'm having same issue, I've tried everything to fix it. Reset my now TV black box. Reset internet, even reset using secret menu (Press menu 5 times then fast forward 3 times then rewind twice on the home screen)
It only happens on live channels for me it seems like everyone else.
I was just on live chat and explained this issue to them. I really hope it's taken seriously and fixed. Glad I've found this and I'm not the only one.