At the Create Issue screen, if you have different context for different projects for the same custom field, changing the project does not update the custom field default value accordingly.

Steps to reproduce
Have at least two projects
Create a custom field and add it to the default screen (tested with URL and Text (single line) types)
Create different context for each project
Edit the default value for each context (use different default values to notice the difference)
Reindex and return to JIRA's home page
Click the Create issue button and check the default value
Change the project and see that the default value won't change according to the previously configured context.

Workaround
After selecting the new project, hit "Esc" on the keyboard or click "Cancel" to close the create issue screen, then click the Create issue button again. Do this everytime you need to change the project.