I published a mod on Steam and everything was going well until my system had an issue and I needed to reinstall the devkit. I had a backup of the mod itself, but not of the entire devkit and did not realize that the Mods.db file was also needed.
Now when I try to publish my mod, I can’t seem to get it to update the existing mod (even if I try to set the ItemSeamId to the old Mod ID).
Is there any way to recover from this so that I can update my existing mod?
Thanks.
Just ran into the same problem.
I had to modify the MODs.db file in this folder:
C:\Program Files\Epic Games\ARKDevKit\Projects\ShooterGame\Saved
But before you change the file close ARK dev Kit completely, because it seems to be actively accessing it. So close the app then change the file data.
That file has the mod Steam ID number and change notes and stuff. I updated the MOD ID number with the number I needed and added a new change note just to see if it shows up when I open the Ark Kit. Then restart the devkit and open the cooker. click on your mod and see if it read your new notes. It worked for me. Next I uploaded a minor change and it went into the original mod ID number. 
That folder Saved was hidden at first so just type in the address so it will show up.
thanks for saving my day xD