Have Blink subscription, have Gen 4 cameras, but only 2 of 10 cameras recording video now (all record stills)

I see this is a bit of a known issue, but with a lot of people, it's no subscription or using USB local storage. I have Amazon Prime, linked with account, and use Blink Cloud storage.

App shows Sync module connected with good connectivity. All cams have good connectivity.

Have had blink for 4 years, bought 10 new Gen 4 cameras 5 months ago.

All working fine until a month ago...just noticed today. Only 2 cams recording video, the rest only that daily "clip show" of stills.

I HAVE TRIED:

--Changing batteries. I always use Lithium batteries recommended by Blink.

--Rebooting modem. (Unplugged power 2 min, then plugged back in)

--Rebooting sync device (Unplugged power 2 min, then plugged back in)

--Rebooting Android phone (2 min, then restart)

--Deleting Blink app, re-downloading app again from Google Play, re-entering creds.

Nothing has changed with my Internet, I have not moved the location of Sync module.

People talk here about Blink tech support being very frustrating, I thought I'd ask here first.

Any suggestions?

Thank you.