Why are my assets dissapearing?

This might turn to a rant, but I just don't enjoy returning to a project and realizing that some assets are missing from the screen that were previously there. I don't know if they were accidentally deleted somehow because the software was running very slowly or through some other means.

All I know is that it was unintentional and now I have to spend time recreating those assets again, given that there are no previous versions that can be recovered (not sure why either).

There continue to be frustrating aspects of Storyline that result in these situations, including very slow speeds and limited recoverability (at the mercy of Windows Explorer). Maybe this can serve as feedback, but I do think there should be an easier way of recovering earlier versions of a Storyline project...