When I connect my bluetooth headphone everything works.
But when I pause the audio/video for a few seconds and start it again, the audio gets interrupted for about a second every 2-3 seconds.
When I turn bluetooth on and off the issue is fixed until the next time I pause.
Very annoing, anything I can do?
This problem occurs in many headphones and I also faces this issue with my headphone but this problem doesn't occur in my bluetooth neckband.
So this problem may be with your headphone.
I have that happen with mine sometimes, too. I turn them off for a moment and back on and they work fine. It is because when the bluetooth signal is interrupted by pausing the playback or something else, it can get stuck.
Also tip if your viewing online the connect can lag after a pause due to the interruption. This is unfortunately one of those quirks with technology. As posted above once you turn them off for a moment and back on and they work fine.
The headphone works fine with my old MacBook and with a windows pc, so isn't this a Linux problem?
I didn't realise how much I pause audio/video 
My Avantree Bluetooth headphones do it on my Sons Windows gaming machine, too. It's actually the reason I have them. They were supposed to be his. But they work better on Linux than they do on Windows!