In a recent code review, the first(and only at that point) changeset had a file that was deleted. The diff for this file showed all red (as I would expect) both in the By Changeset view, and also when viewing By File
When more changesets were added to the review, the deleted file shows "(No changes)" when viewing By File, but the changeset it was deleted in still shows the correct information when viewing By Changeset.
The expected behavior is that a deleted file should still show as being deleted even when viewing the changes by file across multiple changesets.
I have another review where the same "no changes" behavior was exhibited, but this time there was no deleted file!.
There are 3 changesets on the review, and in the first one, File A doesn't show up because it had no changes. However, in the last one, file A has changes. When viewed "By File" however, file A is indicated as having no changes.
One thing I noticed this time, (relevant or not) is that File A is the only one having trouble, even though there are other files in the last changeset that are not in the first that are working correctly. File A is also the first file listed in the last changeset.