Starting from Windows 10 (1607) Microsoft enabled file paths more than 256 characters.
Autodesk even have an article for that:
https://knowledge.autodesk.com/search-result/caas/sfdcarticles/sfdcarticles/The-Windows-10-default-p...
Unfortunately Autodesk Map 3D is hard coded to support file paths up to 256 characters.
I think is finally time to remove that restriction.
NTFS supports file paths long 32,000 characters.