I am also facing same problem due to this "+ Create Issue" button in projects sections. This button is creating issue bypassing mandatory fields. We are using Script Runner plugin for the customfield behavior using groovy scripts.
This is a challenge for us, few users created issue using this button by mistake and ended up having no mandatory fields populated.
This project is a "Company Managed project", but if you can let me know how to get this property of project.
We have customized JIRA to accommodate with our requirement of work flow management tool.
We are using "Atlassian Jira Project Management Software"
Please suggest us any work around or any solution to disable this "inline issue creation" block.

