I created an HDA in Houdini, put it into Unreal, and then used Engine Sync to fix the problem. When I turned off Engine Sync, all my work in Houdini was lost.

Should I keep the original file open, open a new Houdini, sync it, work on it, and copy the nodes back to the original?

When I turn off engine sync, it doesn't even turn off properly. There are many situations where I have to force quit Unreal or Houdini.