Revo Gallery 1.5.0 - Images won't delete

I'm having a problem with not being able to properly delete images from albums in the Gallery. When I right-click, select Delete Image and confirm, the image is not removed from the album. However, the image IS deleted from the server, even though it's still showing in the album. Has anyone come across this before?

Using: MODx 2.2.2, Gallery 1.5.0, PHP 5.3.3

Update: I do receive an error message in the log, as follows:



I have attempted to clear the phpthumb cache, with no change.

This issue occurs in both MODx 2.2.0 and 2.2.2, and Gallery 1.4.0 and 1.5.0.