there seems to be a small bug that the image source is not set by the Guassian Convolution node and the Local Thresholding node. After any of those, the image source is empty. I didn't do a exhaustive search for nodes with that behaviour, maybe there are more.
While playing around with the metadata, I also found out that when the metadata of a 3D image is transferred to its 2D projection, there is no warning, but the resulting image is not shown anymore by the Table Cell Viewer. The preview remains, however.
For completeness, is there a reason why the metadata cannot be set on Labelings?
For the transfer of metadata, I used the Transfer Metadata node. Just try to have a look at the resulting image. The Table Cell Viewer does not react at all when clicking on the image preview in the table. Especially, no image is displayed and there is no dimension ruler at all.