Cluster Saving Issues

Hi - I'm relatively new to both rhino and grasshopper and am having a rather odd issue. For the last couple of months i've been working with a cluster inside a main grasshopper file - it's a large definition but things have been running smoothly up until now.

My typical procedure when saving my work is to save and close out of the cluster, save the primary GH def, and then to save my rhino file. Occasionally, the dialogue box will open informing me that i have unsaved GH work and so i click the save icons there as well. No problems.

However, as of the last couple of days, I open my current primary GH def and the cluster def has reverted to a previous version. This has happened 3 times and although i redo the work and resave the file, the next time I open the file it has reverted back to the same old place.

I've checked autosave but there are no files as I assume it deletes them once I do an official save at the end of the day. The cluster is also not exported or referenced anywhere else. I do have various versions saved within different primary GH defs, but don't open any but the most recent.

Does this sound like something familiar or fixable by changing my workflow? Any insight would be greatly appreciated.

Sarah