Yeah, we made this plugin as we are working with a number of photographers — who were not happy with the imagequality of GD.
Do the Edit Media page still work? Do you still see image dimensions and such?
The warning itself should be harmless, though a bit weird. We try to note which images have been resized using IM on the media library pages. The warning means that we didn’t get the attachment metadata.
I’ll clean up the warning itself for next version, but I’ll need to investigate why we might not get the metadata to make sure nothing bad is happening.
