The 4.17 preview 1 build is available in the launcher now: Unreal Engine 4.17 Preview - Announcements - Epic Developer Community Forums
It includes a significant number of bug fixes and improvements to Blueprints and has resolved several repros for data loss we’ve gotten. There’s no guarantee that your case will be fixed (many different issues have similar symptoms), but I’d recommend giving it a try on a copy of your project both to see if it works better for you and to catch any potential regressions before 4.17 final goes out (we did change a lot of things ^_^).
Note: You may see an increase in warnings or errors as part of 4.17; there will be more info in the upgrade section of the full release notes, but the summary is that we now catch and warn on various problems that either silently failed in previous releases or worked only intermittently (e.g., in uncooked but not in cooked builds). These warnings are much less likely to affect BP only projects or recent BP + C++ projects, but in long-running BP/C++ projects, there will almost certainly a be a few warnings about missing BlueprintType or BlueprintReadWrite, etc… Related to this, we also introduce the concept of orphaned pins which make refactoring issues easier to catch and recover from. As an example, if you rename a parameter on a function in BP 1 that was called by BP 2 and save 1 but don’t save BP 2, then close and reopen the editor, BP 2 will now report an error about a missing parameter with the connection to the old pin preserved, rather than silently dropping the connection on the ground.
Cheers,