1-1 Association returns empty though it has just been filled
I have an dossier entity where I sometimes to add notes to. When I open a page to write the note, I first call a microflow where I create an object for the note and associate it to the dossier object via a 1-1 association. When I open the dossier object in a dataview and try to retrieve the 1-1 association (which I just created in the microflow) in another dataview, it returns empty. However, when I fill the association from the dossier object, it suddenly works. When I fill the assocation from both sides, it doesn't work either. I thought it didn't matter from which object you fill a 1-1 association. Does it?
This is a bug that I have also noticed sinced moving to Mendix 6.5.1. I have a ticket open for it  and a working test project (or should I say not working?), so hopefully a fix will come soon.
So for all who are migrating to 6.5.1 : check all 1-1 associations if the updates come through.
SQLserverquery (If you have MxModelReflection ) :
where association owner = 'Both'
If the association update does not come through then create or update the association from the other object side.
Jan Joost Duijvestijn
Try both... depending on how the relation is defined.....