ALL Blender models disappear after update

Ok, I opened up a project after the latest Unity and Blender updates, now EVERY Blender object is missing. They are still in the folder, but inside Unity I see "Missing Prefab" everywhere and the Blender models are no longer showing their thumbnail. I cannot drag them into the Unity scene. In the past you could include Blender models in a Unity project and Unity would do all the FBX conversion in the background. What changed? And, more importantly, how can I relink the Blender stuff into my project?

 

After some research, the official Unity manual says that when you drop a Blender file into the Unity scene, Unity communicates with Blender and does some behind-the-scene conversion. Apparently this is no longer working. I tried rolling back Blender to an older version but still no luck. Is is possible to roll Unity back to a previous version?

 

Oh, and I just confirmed.....this issue seems to only affect the PC version of Unity.

 

I right clicked on a blender file object in Unity, and pressed on Re-Import.
Works.