I'm in a team with Daniel Hauser and with HANA Studio SP7, we noticed that most of our .procedure objects would not open in a procedure editor (like they did with HANA Studio SP6) but rather in an XML editor.
We found out that this behaviour was dependent on an XML attribute called procedureType. When procedureType="", which was the case for most of our procedures, it would open in an XML editor. When procedureType="procedure", which is the case when you create a new procedure, then it opens in the proper editor.
Doing a corresponding search-replace in all our .procedure files actually fixed the problem.
Maybe others have run into the same glitch, so hopefully this information is helpful to them.