Hi @OracularSheet83,
This topic is for what your problem is about. The non-ascii letter(s) in your Windows 10 account name. Read the notice at the top of this topic.
This problem effects various aspects of MSFS from flight planning, navigation, saving/reading of flight plans, etc. (Again, this is mentioned at the top of this topic)
If you read posts above in this topic, as I pointed out to you in a private message, you will see that changing the account name in Windows, will NOT correct the problem. Changing only makes a visible display change, not a programmatic change.
The only way to correct it at this time, is to create a NEW user account on your PC that does not have any non-ascii characters.
Again, file a Zendesk ticket on this so that the developers can fix this as what was mentioned to you in the private message I sent and is also mentioned in this topic.
Here is the link to Zendesk:
https://flightsimulator.zendesk.com/hc/en-us/requests/new