I need the mobile app to properly sync my 3,500 contacts that are stored in folders in 365. Not syncing renders the mobil app useless.

Hi there,
Thank you for using Outlook and letting us know about your current experience. We really appreciate your support.
We are so sorry this is happening to you. This is not how it’s supposed to work. But don’t worry, we have helpful and knowledgeable colleagues at the Help section of the app that would be happy to address this concern. Please reach out to them by going to the app’s Setting > Help and Feedback > Contact Support
We look forward to fixing this for you.
All the best
The Outlook Mobile Team
PS: Please use the Help Section of the app for any questions, we are not able to see replies to this address.