first of all thanks for the support!
I have replied to you in e-mail, with a screenshot of the problem with raw data in rover mode. Of course I have the switch in the correct position (A) but the error message is still there.
Ragarding your app: I linked the GNSS services I am using, and they are all free, you just have to register, if you want to try directly with them. But I assure you they work with Lefebure Ntrip client, so there must be something else in your app.
And then, about the 12 max satellite problem in the Lefebure ntrip client: you can see in many videos that the app is fine and with other gnss receivers it shows the satellite number correctly, even in your video from your channel (with the old Alpha unit, I guess) it shows 20 satellite: https://www.youtube.com/watch?v=BbSGytKrWr0 , so probably the Lefebure app is not the problem here.