A500FU calendar reminders/notifications issue after Marshmallow update

[grongobar]

After update to stock marshmallow the notifications/reminders from calendar are not working anymore.More specific if I create a new reminder for the same day,everything goes normal,but if there are more days between notificatios they don't appear anymore.I tried to uncheck battery optimisation for any app related to calendar,without any succes.I installed other calendar apps,no result.Revert to factory settings,same thing.
Has someone encountered the same problem,and do you have by chance any sollution ?

 

[grongobar]

Ok .I figured out that it works only if the phone is connected to internet,which is strange because it shoulden't have anything to do one with the other.This doesen't solve my problem because I cannot stay always connected.Any help would be appreciated.