No more notifications since v6 (android)

Hi, using k9 mail on my samsung s7 edge (android 6.0.1).
Some days ago I installed v6 and notifications when receiving new mails stopped working. No more sound, no more notification in the top bar. I have set k9 mail to check mails by hand, not automatically, but when there were new mails I got a sound and a notification. I checked all relevant options and notifications are enabled. I also checked in my phone settings if k9 notifications are allowed and they are as they were before. Any idea ? Thx

Please see No notifications when manually refreshing a folder - #4 by cketti

Is this a typo? My S7 Edge uses Android 8.0.0