Somehow this issue is now in the latest version of .24
Removing the asset (HillTree_02.uasset) allows for the editor to load. Placing the asset back into the content folder causes an instant lock of the editor.
The project was working fine prior to .24.3, so this is probably an engine regression brought on by the version change.
The log shows the hangup as
[2020.04.23-03.57.01:276][597]LogStaticMesh: Building static mesh HillTree_02…
The editor then just hangs forever with no progress in the “loading package” progress bar above 70%.