GMS and BlueMail


I've tried to set up my account on my Android device using BlueMail. The result is, lets say, not perfect. I can connect to the GMS server, I can download emails, etc. But every time a sync occurs, the Inbox folder becomes empty. Then I do a refresh again, and emails appear or not. I tap on an email, and I get an error message, that the email is no longer available. Then I refresh, I see the email, this time I can open it. Then it disappears again.
Have you experienced such behavior?
I can set up my GMS account in gmail, or the built in mail app, and have no problems at all.

Versions: GMS 18.1 build 410, GW 18.0.2 build 131493, Redmi 4X Android 7.1.2. MIUI10, BlueMail 31 October 2018.