I forgot to mention a change I made to the naming rules of sheet files (introduced in version 1.5.1) for DropBox support which may cause problems for some users.
The rule: Sheet files are not allowed to contain parenthesis ( and ) or dashes – in their file name or they will not be shown in the sheet browser.
The reason: To work around a feature of DropBox which will suffix files with extra information to protect against synching conflicts. While these files are often good to keep for reference they will make a mess of your Sheet Browser so I had to protect against adding them.
I understand sometimes you’ll want to add those characters in your sheet file names so I will try to find another solution that works better. Until then please don’t alarmed if a sheet file doesn’t appear. Just renaming in the Finder to not include the aforementioned characters and it will reappear.