Dynamics NAV 2018 "The tenant 'default' is not accessible" when compiling a table

I was doing some changes to NAV 2018 tables and run into this error after import + compile a table as a text file. The error is very confusing, since in this special case I do not have any kind of tenancy, it is just old plain familiar all-in-one solution with normal SQL, normal virtual machine as NAV Server and local development environment.

I tried re-compiling, and the error went even wackier:

"Unable to process table changes because the Microsoft Dynamics NAV Development Environment cannot connect to the specified Microsoft Dynamics NAV Server instance:
Microsoft Dynamics NAV Development Environment will detect a running server automatically.

Check that:
1. The Microsogt Dynamics NAV Server is running
2. The Management service is configured
3. The firewall is open for the management port if remote
4. The server is running with only one tenant
5. Microsoft Dynamics NAV Development Environment is running as Administrator, or
6. UAC is turned off.

After restarting the NAV service, compile went nicely, and I continued working. Next table import+compile -> same errors again.

It appeared that I was missing pos. 5 of the list above...


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