My activity zones are disappearing minutes after creating and saving them. Also have noticed some recordings go black seconds after recording started. Please help just invested in eufy as my surveillance solutions. 5 cameras in total.
eufyCam 2 Pro
System Version
3.8.1
2020-09-11 16:42:06
Subsystem Version
1.0.70-20200706
2020-09-11 16:40:59
Android app version
v2.1.0_698
Happens with apple app also, unsure of version.
5 cams at once was a hb2 killer for me, had to delete one to test a 5th.
Not a solution but maybe try removing one and trying again.
Mine all went back to the seller, except the awesome indoor cam that watches over my dog.
I have 4 cams and a doorbell, and which work fine. Support told me the max is 6 cams.
The android app update 2.0.1 is very buggy, so it may be related to that.
Lost all activity zones from all four 2c cameras as well. Noticed that today and after i setup up them again all disappiared again so looks that is not only problem with your system… one more problem at me as well 
Let’s see when this will be resolved or we have to live with that bug as well like with inactive cameras, missed events, false alerts…
If anyone else is having the same issue it seems to be the lastest app update. I used an older version and it no longer seems to be a problem.
It was just fixed in 2.1.1_705 that I got on Android earlier today. Had to recreate the zones.