Read/Unread filter not working as expected

Checklist

• I have used the search function to see if someone else has already submitted the same bug report.
• I will describe the problem with as much detail as possible.

App

Thunderbird for Android

App version

18.0

Where did you get the app from?

None

Android version

12

Device model

moto g22

Steps to reproduce

Select the read/unread toggle on Inbox

Expected behavior

My understanding of the expected behaviour of the 'Read/unread' toggle based on feedback received when I reported this issue in the Google Play Store is that selecting the toggle either turns the feature on or off:

• when turned on, I should see unread emails before my other emails
• when turned off, emails are listed in the descending order they were received

Actual behavior

My inbox is sorted by either seeing all of my unread emails first (followed by all read emails), or my read emails first (followed by all unread emails) according to selecting/deselecting the Read/Unread toggle. Selecting the Read/Unread toggle only produces one of these options. I want to see all of my emails in descending order of receipt (standard email sorting). This should be achievable by turning the toggle 'off', but this is not how the toggle is currently working.

Logs

No response

Start by reproducing the Read/Unread toggle on the Inbox using Thunderbird for Android 18.0 on Android 12, as described in the issue. Trace the toggle's sorting behavior and verify that turning it off restores descending receipt order, while turning it on places unread emails first.