Shared Accounts for a Pack in Published Docs

I’m trying to do a Cross-Doc Action in a published doc

In my published doc I would like to allow people to use a cross doc action into a separate doc.

I’m trying to add a “submit your doc” feature to the play doc, but I don’t want the source doc to be permanently editable. That means that I’ll have to store their submissions in a separate doc.

I thought I could achieve this with a Cross Doc Action. It used to work, but now it seems I cannot hit submit, even if I’m logged in.

This is strange because I set up the credentials as a shared account:
image

Meanwhile, if I’m logged in with my main account on the published page in play mode it does work.

So it would seem that what needs to be supported is shared accounts for a Pack in published docs.