1- on OfflineSurveys -> if you enter A, then the validation message will be Red... correct?

it is, BUT it should not! In the web-based survey it works correctly.
For A,B,0,1 it should not be red marked.

2- on OfflineSurveys -> if you enter A and press submit, then the popup will show... correct?

Yes, BUT it should not! Because A is an valid input.

3- on OfflineSurveys -> if you leave the field empty and press submit, then the answer will be saved without issues... correct?
In this case yes, because it is not an obligatory question, so NULL is also an valid answer.

I have created another survey with an working validation (without | OR statement) and one not working see attachment.

now I understand , please give me a couple of days this fix this

We have pushed a release... it will reach 100% rollout by Monday (you should get update notification by Monday max)