This came up in another long, confused thread about other things, but it deserves a post of its own, so it doesn't get lost....
If you have a fairly typical title and comment for an image, not even anything long or wordy, captions on the image thumbnails are virtually unusable with the masonry layout.
If you select below as the caption placement, the caption "steals" space from the image - the resulting images look like pano's. See below.png.
If you select any of the other caption placement options, the caption doesn't use the available width of the thumbnail, so that even a short caption yields scroll bars. See centerbottom.png. And commentShort doesn't seem to be working in this case.
This is with default settings other than the thumbnail layout and caption placement.