On day 2 of MSFS 2024 I opened the SDK to work on an airport. All went well, I compiled it, closed the project and exited back to Free Flight. I noticed the SDK menu bar was still there, so I went to close Dev Mode, but the exit button was greyed out. After trying everything, including rebooting, the SDK menu bar has been there ever since. One of my friends has the exact same issue.
The only way to “exit” Dev mode is to disable it in the advanced options
Duplicate of this post: Exit Dev Mode menu item cannot be selected