I am using the Juicebox pro plugin with Lightroom 6.
When panorama photos with an aspect ration of 3:1 or even 4:1 are in the photo gallery their thumbs get blurred with increasing aspect ratio.
A sample gallery showing this effect you can see here: www.wolfram-foto.de/test_gallery_usa/index.html
The reason is probably that the down-scaled thumbs in the export directory have a fixed width (170 pixel at the default setting of 85 x 85 for the thumbs). With increased panorama width the thumb hight gets less then 85 px and will be up-scaled for display.
Making the thumbs width wider (e.g. 170 x 85) improves the thumbs of panaorama photos, but causes blurr thumbs for portrait format photos. So it does not solve the problem. Are there any workarounds rather then placing manually down-scaled photos in the export directory?