[Plugin: NextGEN Gallery] strange line breaks using custom sort order in gallery view

Hi, I’ve been using “custom” order of thumbnails in the gallery view, but it has started producing strange line breaks in the display of the photos… as you can see here:

https://jennifersproule.com/gallery/?album=all&gallery=3

interestingly, if I change the order of photos to be sorted by date or by ID, the line breaks disappear and everything looks as it should.

any help would be appreciated!

https://www.ads-software.com/extend/plugins/nextgen-gallery/