Did my Project just corrupt itself? (Null StaticMeshActor Root Component?)

Development Programming & Scripting Blueprint
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I’ve been working as usual on a BP for a StaticMeshActor (Parent) and when I went ahead and tried to compile. That resulted in Error: Default__BP_BaseProp_C is not valid. See the MapCheck log messages for details. The Map Check tells me the following: Default__BP_BaseProp_C Static mesh actor Default__BP_BaseProp_C has NULL StaticMeshComponent property - please delete

Again I have changed NOTHING about the mesh components but upon further inspection i noticed that UE seemingly changed the expected “Static Mesh Component” into “Root component” and selecting that doesn’t even show any details anymore.

So what exactly happened here and how I fix and prevent this in the future?

Observed result:
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Expected result:
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This is how the properties look. How can assign a static mesh and fix this?
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Re-parenting fixed the issue.

For anyone interested in the steps: Character Mesh suddenly disappeared. - #19 by DeOceanPirate