I imported a mailbox from Mail.app to EagleFiler with no problem, but when I sort by Tags, not all the “Replied To,” etc., messages (with their original status tags from Mail, nothing added) are in one place but are instead broken up into islands, mainly large but still not all together with each other.
Does the sort order make sense if you show the Tag Names column? Perhaps there are other tags combined with replied that are affecting the sort order. Tags that don’t have abbreviations set won’t show up in the Tags column but will show up in Tag Names.
If you can send me a screenshot or a small test library, that would also help.
If you are just trying to find all the messages that are replies, you could click on the replied tag.