Not sure if this is user error but it seems that query field is not available as a source for a page/screen if that page previously had another source selected. Here is what I’m seeing :
Create a new table. Add some items in column one. Create a query in column two with a source of another table that is filtered by “this row” and looks at the items in column one. Go back to the layout. Take an existing page/screen in the menu and change the page source to the new table. For the collection, choose the “source” drop down. The new query column is not shown, though it would be expected to be there.
Create a new page/screen with the new table as the source. For the collection, click the “source” drop down… query is there.
Now change the page/screen source on this newly created screen to another table. Then change it back to the new table. Hit the source “drop down” for the collection…query is not available.
This is just a sample obviously (the query doesn’t actually make sense), but I wanted to try to recreate from a newly created app, so I just kept the default tables and added a table and created a similar query.
I tried to replicate what you described, but I was not able to get the same behaviour. That is, the query column remains selectable as a collection source after switching the screen source out and back.
I must admit though, it’s very easy to get a bit lost when doing this, so you really have to pay careful attention to where you are and what you are clicking on.