Scrivener on my MacBook Pro has suddenly developed a distressing tendency to delete text without being asked. It happens in this way: I am setting up a bulleted list, after which there is a block of separate text. Each time I try to go back into the list and add another bullet point, the moment I press enter it deletes the block of text at the bottom. At first I thought that I was accidentally selecting it, but this proved not to be the case. I have tried selecting and deselecting it, but the same thing happens. I am currently having to select/copy the text and then, after it has once again been deleted, go back in and paste it again. This is clumsy.
Have you double-checked to make sure the text is actually being deleted, or does it just visually vanish? A good way to test this would be to hit Cmd-A after the problem occurs, and then copy and paste into a TextEdit and one of Pages, Word or LibreOffice. This will eliminate any conditions that exist in the Scrivener editor itself. I would also recommending using the Edit/Paste and Match Style command to ensure that no rogue formatting is being carried over. If the text is visible using that paste method, then try again with standard rich text paste and see if the problem carries over to one of these programs.
TextEdit uses the same text-engine as Scrivener, so using that program to test with will help check for underlying OS X bugs.
The other word processors I recommending testing with do not use Apple’s text engine, and so it should not exhibit any of the same bugs or quirks.
Finally, let me know of any conditions in Scrivener that seem to exacerbate the problem. Does using Full Screen or Composition mode change the frequency? How about using wrap-to-window instead of Page View (or the other way around). Does it happen with short lists, with new documents or just this one in particular, etc.