Directly after starting the ML App Simulator, it becomes unresponsive and displays "Restoring Application Simulator Session..." in the Device View tab; in addition, it takes down the complete ML Hub.
I am on an Apple M1 running macOS Sonoma Version 14.0. The App Simulator worked a couple of days ago on this machine, and it also worked in combination with Unity 2022.2.0f1 (usability and performance of the App Simulator are a different rather sad story 
).
After getting the above mentioned "Restoring Application Simulator Session..." unresponsiveness and not being able to solve it, I removed the entire ML Hub and all files in my home under "~/MagicLeap". I reinstalled the ML Hub but I do get the very same result. In the process, I killed the ML Hub several times; there may be some stuff still lying around somewhere. The log file shows "2023-10-15 12:16:54.145 ERROR SceneViewTextureViewerPart: Failed to read Simulator configuration", which seems to somewhat support this assumption.
Maybe the solution is as simple as deleting some inconsistent state somewhere?
ML, I really do like your device - a lot! I hope you will improve your software stack and usability in the month to come. One improvement should be an easy way to do a clean and complete uninstall of the ML Hub to then start afresh.
Thank you!
Stephan