I have a survey with 7 groups and about 5 questions each. I've ordered all the questions using the drag and drop function in the survey Structure area.
To clean up, I use the 'Regenerate question codes' by 'question group' from the main survey overview top nav bar.
Everything is renumbered but, this is the ordering sequence that's returned. The group numbering numbers the bottom group #1 and inside the group the last questions is #1.
G2Q00002
G2Q00003
G2Q00001
G3Q00002
G3Q00003
G3Q00004
G3Q00001
G1Q00002
G1Q00001
The result is when my survey loads the bottom group G1 appears at the top of the survey, followed by G2 and so on. And the questions display in a similar order.
I tried creating a test .lss but, everything works great when I do that. In the survey I'm working on with the problem I had used the old re-ordering drag-and-drop function until I read that the method described above is the updated version. So, perhaps I screwed up some code in the DB doing that?
I'm have the Community Edition Version 3.7.2+180508, using the Vanilla theme, on a Centos 07 install using Postgres 10.
We are aware of this issue and are currently fixing it.
This is a known problem, that only came up on PostgreSQL so far.
I can keep you posted on how far we are fixing it.