Check the BI logs to see what it says. Not sure that's what it is but BI drops cams much easier than some other VMS/viewers. And it takes a little while to recover when it does so you'll see it more. When it happens, check the time stamp in the Amcrest/on camera and see if it's actually moving or stalled. e.g., Some crappy Wyze cams I have can stall out for 5 or 10 seconds and their app looks like everything is fine unless you look close to see that the time's not moving. Never drops them, just shows a static image. BI balks immediately and drops them and throws up the problem screen until some time passes after it recovers.
A restart of each individual cam from the console straightened it out.
Seems Macrium Reflect was hogging the free space on the Seagate 8TB until the drive was 99% full. Screwing with the overhead BI needed to write and read. I had not restricted the backup disc image folder to a size equaling or exceeding the Blue Iris " new" folder size of 4TB.
Then I deleted about 10 Windows .ISO's from XP, 7 Vista, 8. which increased free space from 28GB to 64GB.
Then for good measure I moved ahead about 11 months in versions of BI...
Now I'm cloning the Seagate 8TB to a new WD82PURZ.