Unread badge intermittently shows empty (no number) with conversation highlighted, despite no unread messages

[kingpurest]

Checklist

• I can reproduce the bug with the latest version given here.
• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
• This issue contains only one bug.
• I have read and understood the contribution guidelines.

Affected app version

1.9.1

Affected Android/Custom ROM version

Android Version 16

Affected device model

Samsung Galaxy s24 ultra

How did you install the app?

F-Droid / IzzyOnDroid

Steps to reproduce the bug

Spontaneously occurred during normal texting. Affects one specific conversation. I was not performing any unusual action; the badge appeared as an empty bubble with the conversation row highlighted in the middle of an ordinary text exchange. Attempts to intentionally reproduce it afterward (sending messages, receiving messages, deleting messages) were inconsistent and did not reveal a reliable trigger

Expected behavior

When I read a message I've received, all indications (bubble, highlighted text, position on list) of an unread message should disappear.

Actual behavior

Empty bubble appears next to one specific conversation, contact name and text preview highlight white as if I have unread messages.

Screenshots/Screen recordings

Screen_Recording_20260731_132017_Messages.mp4

Additional information

Force-stopped the app
Cleared app cache
Rebooted device
Toggled app language (Spanish → English → back)
Set Fossify as default SMS app (confirmed already was)
Deleted recent messages in the affected thread
Tested sending a new outgoing message
Tested leaving an incoming message as most recent
Tried tap-and-hold → "Mark as read" (works temporarily, ~5 sec, then reverts)
Checked delivery/read report settings (not the cause)
Checked for duplicate/merged contact threads (not the cause)
Updated app 1.9.0 → 1.9.1 (persisted)

None of it produced a reliable fix or a consistent trigger.

[marvinctl]

This duplicates #609: both reports describe an affected conversation showing a blank unread badge and reverting to unread shortly after being marked as read.