PSE 15, Win 10, no thumbnails for iPhone jpg

I recently installed PSE 15 on a Win 10 pc.  JPG photos from my camera (6Mb) & from an android phone have a thumbnail when imported. 

For the first time I've imported jpg photos from my iPhone (4Mb) and all I see is the hourglass icon for these photos.  This seems to point to there being something different about iPhone jpeg files.

Following other answers I have tried:

      editing the size restriction in the registry - no success

     deleting the thumbs cache file & let PSE rebuild it - no success.

Please can someone suggest a solution?