Google calendar app reminders: sync problems

Reminders are non syncing properly in app and widget on Android (ok on wev).
Here's my scenario, tested on a phone and a tablet.
Add reminder in app: it shows on Web but not on app and not on widget.
Force sync in app: still nothing on app and nothing on widget.
Add normal event in app: even is added on Web and on app and on widget AND reminder now shows up also on app and on widget.
Delete reminder in app: reminder is deleted from Web but not from app and not from widget.
Delete event in app: event is deleted on Web and on app and on widget AND reminder is also deleted from app and from widget

It seems the problem is a display problem.
For example, if I modify a reminder on app, the changes appear on Web but not on app, still if I click the reminder in app it is opened with the changes made.
Also, if I delete a reminder from app, it is deleted from Web but not from app, yet if I click the reminder on app I get an error "reminder not found. As a proof: if I set a reminder it does not show in app but I get a notification when time comes!!!!!!!

I am having the same problem on S6 Edge+

On the calendar forum someone us suggesting it's only a Samsung problem.

Anyone else?
Thanks

Notification reminders

I like option in setting to remind me about notification in 5 minutes. But it reminds me with sound *and* vibration. Is there any way to leave the sound only and turn off the vibration? I do not use vobration at all in my settings or profiles, it is present only in this reminder which is not comfortable.