keep bumping it every so often, or if you start beta testing 11.1, add a link to this thread in your bug reports.
Don't get frustrated. The dev team will be aware of it. I posted about it all through the v11.0 beta testing, and a little attention right at the end left us in the situation we have now. While not ideal, it's enough for me to know how to get desired results from what we have. I don't import playlists of already imported files all that often anyway, and I don't think many others do either else there would have been a furore.
I mostly import m3u's along with the files and then delete the actual file. MC retains the playlist in the tree and keeps it sync'd with any subsequent file changes. If I need an m3u for an external program, I just export it as required.
Now, to your problem...
Invariably, with MC, there are many ways to skin the same cat, so, would an entirely different approach work for you?
How about, instead of going through the "select all files, click file>export playlist, complete the options dialogue, click OK" you try this...
In the action window, click on build playlist, then on create new. use the dialogue to name and place your new playlist.
You should notice that your new playlist is now showing in the action window, empty, and prompting you to drop files.
go to playing now, select all, drag, and drop on the playlist action window.
You have now achieved the same result you appear to desire in your first post. Would that system work for you? If you need the actual m3u file for some other purpose, you could still use the export playlist tool.
-marko.