Hub on Android can't save drafts. Device is busy...

Running the latest version of Hub and Blackberry services on a Samsung Galaxy Note 8.
When I try to switch to another app, or back to the home screen, while composing an e-mail, the message is completely lost. A small popup is displayed at the bottom of the screen, saying the draft cannot be saved because the device is busy.

This is very frustrating because this makes it impossible to lookup something while composing an e-mail. This also makes it impossible to attach any kind of file, except if I remember to attach the file first before typing anything else. In an unmodified blank message I can attach. As soon as I type something, I can no longer attach because the draft cannot be saved again, and the Hub now also crashes.

This problem was already there on the previous versions of the Hub also. Since the latest version (couple of days ago), the problem has gotten worse: now the Hub also crashes when the error is displayed, and I have to restart the Hub.

I also performed a test with a Huawei Mate 9. This one does not display any error, but in fact has the same problem. The draft is not saved, and all changes are lost.

A test with my Blackberry Keyone shows a different situation: the draft is saved, but only visible when I use the setting to also show sent messages in the Hub. Before this was never needed.

I already removed all Blackberry Apps from the device, and did a new install, but the problem remains.

I contacted Blackberry Support, and they try to help, but when I create a bug report on the device, the ZIP file can not be opened. Maybe this is a symptom of the same problem?

The email account is using Microsoft Active Sync (Exchange) tot connect to an IBM Domino Traveler server.

For the moment I am a bit desperate because this problem is bugging me for a couple of weeks now, and it makes it very hard to keep using the Hub.

Any suggestions are very welcomed :-)