Bug has been fixed in recent update by now being unable to publish a model over a package. 
Do not attempt this unless you want broken packages in your inventory which you can’t insert into studios or update!
I’m only certain this works when AutoUpdate is disabled and haven’t tested it with AutoUpdate enabled. I assume there’ll be a similar result if you replicate this bug with AutoUpdate enabled.
How does the bug occur?:
- Create a new package using “convert to Packages”
- Publish something to the package using “save to Roblox” (sorry, didn’t mean package)
- Delete the parent instance of PackageLink and restart studios
- The package should no longer appear in Game tab -> Packages and attempting to insert the package using Toolbox -> Inventory -> My Packages will yield the warning “Toolbox failed to insert asset PackageId here …: Forbidden” the first time then afterwards yields the warning “Toolbox failed to insert asset PackageId here …: Bad Request”
This is probably because the package isn’t in the user’s inventory and copying is disabled on it by default; thus, preventing it from being inserted and yielding that warning.
Other info:
- I am aware there is a possibility to backtrack by going to a previous version of the place or to another place that has it and snag the PackageLink, but an issue is when the developer didn’t save between the time they create the package, delete it, and publish something to it.
- When attempting to try and backtrack via ROBLOX’s website using Develop -> Models -> Configure Model -> versions, it says it restored the ‘model’ to a previous version, yet going back to Roblox Studios the issue still persists. Shouldn’t they be classified as Packages on the website and not Models?
- You can always make another one, but there’s a chance a developer has done a lot of work on specifically that Package and will suffer the loss of what was done on it.
My thoughts of how to fix it:
The best option is to not even give the option to publish to a Package using “Save to Roblox” and also attempt to have it be classified as a Package on ROBLOX’s website instead of Model. This will prevent new developers not to get confused and will prevent the mistake of publishing something to the Package and lose the ability to use that Package all together.