Uncompressed MSCX files get saved as zip-compressed files if the extension is "Mscx".
Here's a bug: if you're using unpcompressed MSCX files, and you happen to have one whose file extension is unconventionally capitalised ".Mscx", then it will load correctly. However, when you save the file, it will be saved as a compressed file (the "MSCZ" format) even though its filename still ends in ".Mscx".
Comments
Then, when you next go to load the file, there is no error message, but the file displays in MuseScore as a blank page, which is somewhat terrifying. The fix is to rename the file to end in ".mscz", so that it will load correctly, and then re-save it as ".mscx" (if that's your preferred file format).
(Marc: of course I'm aware that images don't get handled correctly in MSCX files, but I never use images, and for lots of other reasons I prefer to keep all of my music stored uncompressed.)
In reply to Then, when you next go to… by Solomon Douglas
That is understandable. There are potentially a few other things that could be lost by storing MSCX - a thumbnail, for instance, but there are advantages as well. Anyhow that's the first rpeort I've heard of the capitalization issue, so feel free to submit it to the issue tracker.
Confirmed:
in 2.2.0 nighly 11a58ef
in 2.1.0 871c8ce