I suspect this is a bug...
I've created several scenarios for the game, but when I went to publish the new scenario, I realized I'd lost access to older, published scenarios.
Before:
View attachment 5416569
After:
View attachment 5416569
As you can see before uploading the new scenario "infestation in the all-girls school" (first image) the last scenario I have access to is "Hiverland station 2.3 (MAIN)" but after uploading the new scenario, I can no longer update "Hiverland station 2.3 (MAIN)" since it has disappeared from the list of published scenarios to update.
Note: Deleting published scenarios allows you to access scenarios that had disappeared.