Bridge stops making previews when a new folder is dragged over to be examined. Highly repeatable bug. FOR YEARS.

Summary: Drag-drop a new folder of images to Bridge and about 30 images in it starts making previews on demand.

Steps:

1. It is common for Photographers to quickly divide photos of a shoot into topics. Quick glance at Thumbnails (Windows or Bridge) and move them into folders.
2. Folders contain 100 or more photos
3. When done going through a folder of photos, rating the good ones, Photographer drags the next folder to the Bridge Preview Panel to start rating the next topic.
4. About 30 photos into rating the photos Bridge starts creating Previews one at a time. On demand. This is very annoying.
5. Theory: A Thread making the previews has suddenly died.
6. HIGHLY REPEATABLE. For years. It can happen the first time a new folder is drag-dropped to Bridge. It can happen the 3rd time the next folder is drag-dropped.  IT WILL HAPPEN.
7. My experience: DAILY. Every single day I reach this time consuming problem.

Workaround: Restart Bridge. Sometime repeatedly on days when there are a dozen of topics to cull or rate photos.

Possible factor: full size previews.  (WHY would any other preview be used in Bridge?)

This problem has been reported FOR YEARS.  Never gets fixed.