Below you will find questions with answers that match the question above.
This problem is known for old P3D versions or some files that were not updated correctly.
First please verify your P3D components versions:
You can verify that by running your P3D and checking both Add-ons and Scenery options.
The scenery should NEVER appear twice in the Scenery Library. Correct installation is by add-on.xml which means it will be greyed out in the Scenery Library.
This is mainly because of a SODE issue.
1. Verify if you own the last version of SODE: https://sode.12bpilot.ch/
2. Set your system to show you hidden items.
3. Run your simulator and load the MK scenery that has this problem.
4. Then navigate to: C:\ProgramData\12bPilot\SODE\log
You’ll find LOG files there.
Attach them to the support ticket.