As a Roblox developer, I keep thinking that I cannot overwrite an existing place when calling File → Publish To Roblox As…
This is because the UI only initially shows you starting place of all your experiences by default.
The reason this simple thing took me so long to figure out, was that I had no idea clicking the experience would open up a list of subplaces, but rather, just publish to the starting place of that selected experience instead.
I’ve never had to publish to places from a different place in the same universe until now. I suspected that because subplaces weren’t showing in gridview, that it was not possible to publish them without opening the subplace.