Hello DionPowder, thanks for reporting this issue and we are investigating for the root cause of it.
Could you check if the Basic Tile actors in your map have Can Ever Affect Navigation turned off on associated static mesh component? If that’s the case you can try to turn it on manually to fix the AI stuck issue.
Update on this issue again, with 27.10 released today, the issue should have been resolved and you don’t need to manually update the Can Ever Affect Navigation property again to fix this issue.
Sorry for the inconveniences it introduced, we are working to improve the process to capture unexpected issues like this for upcoming releases.