Gallery app incorrect thumbnail

I think I may have found a bug within the gallery app.

When I go to change/replace an image in a album the output updates but the thumbnail within the album and within the image admin never changes from the original upload.

Perch version : 2.7.8 Gallery version : 2.8.5

I have tried a fresh install of perch but I'm still getting the same results.

I don't think it's connected but I get this error in the image admin page

Array
(
    [type] => 8
    [message] => Undefined variable: filter
    [file] => *path to perch*/perch/addons/apps/perch_gallery/modes/image.edit.post.php
    [line] => 36
)