Status Flags Option Not Working or Missing Coverage?

[DrBrynzo]

I was just comparing two folders I know contain dupes, one is a copy of the same folder from a slightly earlier time. The add-on isn't finding ANY dupes even though the whole folder is literally dupes.

I viewed the message source on a couple, saved them to files and ran a diff with only this result on one of the messages in question:

% diff 1.txt 2.txt
3,5d2
< X-Mozilla-Keys:
< X-Mozilla-Status: 0001
< X-Mozilla-Status2: 00000000

I have Status Flags disabled as a comparison option but maybe these aren't covered by the option? They've been around a while from the looks of it:

https://vincent.bernat.ch/en/x-mozilla-status