My phone number not displayed in system settings

[ZimbiX]

Context: I had to go through Uber Eats' support yesterday since their app was failing to re-verify my phone number using their SMS'd code. As part of the support form, they asked me to submit a screenshot of my phone number. This seems like an odd way to verify ownership of a phone number, but at least on the Cosmo, it doesn't work. Their instructions were:

Android devices

The location may vary depending on your version of the Android OS. For many versions, you can use the following steps.

• Open “Settings.”
• Scroll down and select “About phone” or “About device.”
• The phone number may display on this screen. If not, select “Phone identity” or “Status” then “SIM status”.
• Take a screenshot of your number by pressing the Power button and Volume down key at the same time.

For the phone number, it just says "Unknown". This is with my sole SIM being the physical one in slot 1 - it doesn't seem to matter whether the eSIM chip is enabled or disabled (System settings -> 'Cosmo Settings' -> 'Use eSIM for SIM slot 2').

Device: Cosmo Communicator Android build number: Cosmo-9.0-Planet-02032021-V25