When creating derivatives, the Large Image SP appends a  to the filename of the OBJ. With a TIFF, this selects the first page, if there are more than one, but with a JP2 it selects the first tile, which may not be the "base" tile. (It often is the upper left corner, at the lowest resolution.) An example is attached.
Since it's unlikely the users will be using the Large Image SP for multi-page TIFFs, it seems safe to remove the "", which lets the JP2s be processed normally. I'll submit a PR.