I just noticed that in my selection of Groups where I can save in or move to my Forms some specific Groups don't show up. All Groups were automatically created by Office 365 as underlying structures for Teams. I am owner in the Groups that don't show up.
Which conditions do Groups have to match so that I can move personal Forms to them? When I create a new Form in the corresponding Team per Forms register app, I can see the new form. But I don't get it why I can't see it in the Group selection drop down.