Camera Raw error message, image size too big even when it isn't

I created a panorama of several photos that are 61 megapixels each. Then I tried to edit the composite with Camera Raw (using the CR plugin from within Photoshop). The following error message appears:

• The image size exceeds the maximum of 536.9MP or 65000 pixels on the long side supported by Camera Raw.

Ok, so I decide to crop the image a bit. Now the resolution is 27961 by 16251 pixels. According to my calculations that should equate to about 454 megapixels. Yet, Camera Raw keeps showing the same message.

I have save the cropped version as a new file, restarted Photoshop, even tried in the beta version of Photoshop, but it doesn't matter. Camera Raw still thinks the image is too big, even though it isn't.

Any idea what could be the issue? I guess I can cut up the image in several parts and copy the smart edits, but I would prefer not to, especially since I believe the image should fall within the required parameters.

Oh, and I'm on the latest versions of both PS and Camera Raw.