Some incoming sms / text messages do not trigger / display notification LED / sound though they are shown in Chatty (waking up from suspend?)

Pinephone v1.2 UBPorts CE running latest up-to-date Mobian on SD card.

I have been testing incoming SMS notifications by triggering an authentication text message / SMS via a website, typically after more than half an hour or one hour - suspend is set to 5 minutes but I had used systemctl suspend command in Kings Cross terminal.

Typically with Chatty closed, notifications (modem wakes up phone, blued LED blinking / notification sound) work. However, I've also had several SMS that have come from other sources that did not - saw them opening Chatty.

With Chatty left open, I have had more notification misses - the modem wakes up the screen but there is no blue blinking LED and no notification sound either. However, upon unlocking the screen the SMS is visible in the open Chatty window. I did come to think that the open terminal window was an issue as I sometimes had a notification popup on unlocking the screen saying systemctl suspend completed. However, not using terminal and only having Chatty open still results in some missed notifications.

Every incoming SMS is actually received and cleared from the modem (when I checked there were no SMS listed) and therefore visible in Chatty.

I did have an instance of an SMS not showing in Chatty - possibly because the modem was off when it was sent? Sudo pkill chatty and reopening Chatty showed the SMS.

I noticed there is a 'Receiving SMS is unreliable' issue (#215) but it is related to incoming SMS after sending text messages.