Every single MAS file I try to open just results in no files being displayed. No error message, just an empty file list. I did not try this with B629 so I don't know if it's a new issue in B649.
Weird, I can create a new MAS file, but as soon as I save it, the list goes blank and the status bar says "0 files"... This feels like a must-fix issue before the next public release, otherwise all modding will come to a halt.
< edit > I do however have your 2nd problem (sort of), the MAS file does get created but after the packaging of the MAS is done, the MAS utility window looks like you just opened a fresh instance of it except it has the name of the MAS file you saved in the title bar and the compression ratio in the details pane!
More info: I now remember that opening MAS files did work fine in B629 because I opened one of the Quebec MAS files and extracted the cam file from it when I tried to pinpoint the moving trackside camera issue. This is a new issue in B649. When I open a MAS file with B649 I do get the MAS file name in the title bar, but the file list is blank. @MJP: After you save a MAS file, what does the status bar say? Mine says something like "0 files - Compression: 18%"
Yes after I've saved a MAS file it says "0 files - Compression: 18%" in the status bar. Also yes you're correct on the opening of a MAS file using the B649 MAS2.exe and getting a blank file list, I get that too. The reason I didn't notice before was because I have 'mas_auto_files' associated with an older version of the MAS2 utility (pitfalls of multiple installs lol).
You might know this, but worth re-stating, we're going to put out unstables a bit more often now. They won't necessarily be the release version/candidate.
Ok, thanks Tim, that's good news. I just assumed a release was close since the release notes says "Update 23 (Build 649-unstable, 650-release) Changelog April 10, 2014)".