Could you further describe what the issue was? Would EOF not display the forced strum gems as being larger, or did the note retain the "h" or "(h)" notation below it even after you apply "Note>HOPO>Force off" on it? If you find a way to reproduce the issue, let me know. Did this happen in all non real guitar tracks? I see an issue where the 3D preview won't display forced HOPO notes with the correct smaller size in pro guitar tracks, but that didn't seem to apply to the 2D rendering.
Depending on your luck, Windows may have automatically made a backup "shadow copy" of the settings file. To check for this, right click on the EOF program folder, select properties and then select the "Previous versions" tab. If any older versions of the folder are listed there, you could open the backup copy and salvage the config file.
If I were to create a new note to Force HOPO Off away from another note, it will work the way it is placed but once I drag that note into another note's HOPO range, the Force HOPO Off status (big notes on the 2D editing plane) will turn off and revert back to an auto HOPO (normal sized notes) and it will only toggle between auto and forced on (small note) in an auto-HOPO range. And yes, I only tested this on non-Real Guitar tracks (Guitar Hero/Rock Band-styled tracks). During the "error", I noticed the notations would either be "h", "(h)", or "." (with consecutive HOPOs) but now that big notes (forced strum) show up on a new EOF.ctg, "(h)" doesn't show up any more (I think "(h)" meant auto-hopo).
I was hoping to be able to recover the "corrupted" configuration file but trying to show Previous Versions in the properties any files I wanted to revert back to but that Windows 10 feature never ever worked for me for any saved files I was hoping to recover for anything. Like anything else on my computer, Windows 10 didn't back up EOF.ctg's previous saved versions.