When I have to switch between projects inside the popup creatin screen, in order to display a contextualized customfield (mine or JIRA native), the default value isn't selected.
If I close the popup screen while having the good project selected, and reopen the creation popup, then the default value is selected as expected.
I took a look at JIRA source code with Eclipse debugging, and it seems that the method "void populateDefaults(Map fieldValuesHolder, Issue issue);" from the OrderableField class isn't called inside the popup when switching between projects.
It could help
Good cheer !