Mail flag icons are missing, shows color name instead [STILL]

This is a followup to thread 6668711 https://discussions.apple.com/thread/6668711 from November 2014, with the last reply on October 2017 before thread replies were turned off due to inactivity.

This is still happening. I'm on 10.14.2 on my work Mac mini. Randomly, mail flags will disappear from the Flag column in the message list, replaced by the flag name that I've assigned.

This is normal operation below. I have green flags that I assign to certain message, and visually the green flags mean something specific to me about that message. It's a quick visual identification that makes more sense than text characters in this column:

After an uncertain period of time (pretty randomly, but in the range of a couple days to as much as a week), the colored message flag will disappear from that column, replaced by only the custom name assigned to that flag color:

This even happens in the middle of a day for no apparent reason, with no major system action that I can identify that might have triggered it.

If I expand that flag column, yes, I can read the entire tag name, and I can even identify it by the first letters since that's the only tag with that name pattern.

But it's frustrating that this bug is still happening after 5+ years, across many Mac OS X versions.

The suggestions given, like: "start in safe mode", "uninstall third party apps", "reinstall the OS" make no sense because it's quite clear none of those drastic alleged fixes are related to the problem, and the juice just ain't worth the squeeze to undertake such a massive nuclear option "solution" for an apparently simple bug.

The standard solution is to turn off Classic Layout in Mail>Preferences>Viewing, quit Mail, then restart Mail and turn Classic Layout back on. That does work to restore the flag colors in that column. You can of course widen the column to display the assigned custom flag name to the right of the flag (like shown in this snippet below), but the idea is the default column width is very narrow to just show the flag.

The other suggestion of just quitting and restarting the Mail app (without toggling Classic Layout) doesn't work here.

I've started a log to record each time this occurs, to determine if it's a certain duration when it happens, or some other trigger (currently unknown).

Normally everything is fine. I have a few named flags (shown here), everything's great for a few days to a few weeks, but then BOOM I have to reset the preferences and restart Mail because the flags disappeared in the message list again (they always remain fine in the Mailboxes side bar under "Flagged").

Tell me I'm not the only one that is still experiencing this?

Thanks.