[Plugin: NextGEN Gallery] Carousel style gallery navigation problem

I am using the Carousel style galleries, and the previous / next arrowhead navigation images are only displaying the top half of the arrowhead shape.

I have just upgraded wordpress from 2.9.1 to 2.9.2 and NextGen gallery from 1.4.3 to 1.5.2 and the issue is still there.

An example of the issue can be seen on this page:
https://photos.phase9.tv/nggallery/post/green-zone/page-2

Thanks in advance for any help!

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