PinePhone: text messages aren't shown when in deep sleep

Describe your issue

Text messages are lost when waking up from deep sleep. Calls are working fine when using deep sleep. The phone wakes up on receiving the text message but no notification is shown. The messaging app also doesn't list the text message.

After a reboot, the text message does show up when the modem is ready. When the phone is not in deep sleep, text messages are received without any issue.

Note: I use the latest modem firmware.

What's the expected behaviour?

Text messages are shown in the UI and a notification is created.

What's the current behaviour?

Text messages are received by the modem, but not shown in the UI and no notification is created. After a reboot, the text message appears :)

How to reproduce your issue?

What device are you using?

1. Let the phone enter deep sleep
2. Send a text message
3. The phone wakes up, but no notification is created or shown in the UI
4. Reboot the phone, the message shows up

On what postmarketOS version did you encounter the issue?

• edge (master branch)
• stable (v20.05 branch)

On what environment did you encounter the issue?

Phone environments

• Phosh
• Plasma Mobile
• Sxmo

Other

• No environment
• GNOME
• KDE Plasma
• Kodi
• MATE
• Shelli
• Sway
• Weston
• Xfce4
• fbkeyboard
• i3wm

How did you get postmarketOS image?

• from https://images.postmarketos.org
• I built it using pmbootstrap
• It was preinstalled on my device

What's the build date of the image? (in yyyy-mm-dd format)

Up-to-date 13/11/2020

Additional information