CheckBox Alarm not synchronising Android

Using Joplin on 2 phones android 10 and 1 PC Ubuntu.
Sync between these is through local file. The files are sync with Syncthing.
Version 1.0.333 on 2 phones
Version 1.0.227 on the Ubuntu

I created a small Check-Box note with an alarm on one of the phone.
The note sync’d ok to the other phone and to the PC.
When the time came up, Joplin showed a notification on the phone where I created the note, but no notification on the other phone, nor on the PC.
On the 2 phones the settings are the same: different phones, yes, but same system, and same Joplin settings, and same notification settings in Android.
On the PC, opening the note in Joplin, it shows the date and time of the alarm, but that’s it: no notification anywhere. The Applications/Integration/Notification is on for Joplin in the Ubuntu settings.