Canvas Size can't be adjusted past the original image boundaries (gimp-image-resize)

[teconmoon]

I'm trying to perform a batch where I'm adjusting the canvas size for a large chunk of images, but the plugin representing Canvas Size (gimp-image-resize) doesn't seem to behave as expected in BIMP when trying to expand the canvas size past the original image boundaries.

Example: I have a 256x256 image, and I'm trying to adjust the canvas to 512x512 with an offset of 128x128 so that the original image stays centered in the new canvas. The following settings do nothing, whereas choosing the GUI Canvas Size option in GIMP with the same settings performs as expected.

In BIMP, if the entered dimensions are smaller than the original image, it does successfully crop. This tells us that the plugin is at least doing something, but if one of the axes is larger than the original image boundary, that axis does nothing. Example below: