On the comparison summary the All Items tab does not show items that don't exist in either org.

It is possible to add an item that does not exist in any org (perhaps by mistyping the name of a class/object/trigger/etc.) but the All Items tab does not show those items. It would be helpful if even items that don't exist in either of the comparison orgs were displayed in the All Items list and flagged as not existing. This will make debugging problems like mistyping names easier to diagnose.

I wasted an hour of my time and that of two Gearset Tech Support reps today troubleshooting what we thought was a bug before I realized the mistake that I had made.

I created a filter and did a comparison only to realize that I had missed a couple of items from my filter. I then added the missing items from my filter and updated. When I re-ran the comparison the items I had added were not in the Items list on the comparison results page, not even on the All Items tab. We assumed that there was something wrong with the filter, or the gearset was for some reason using the older filter and ignoring the new one.
It turns out that when I added new items to my filter I typed them in and clicked the Add button, but I mistyped the name of the classes I was adding. As a result the items I added were showing in the filter as valid but when Gearset ran the comparison they were ignored because they didn't exist in either org. If those items had showed on the All Items list (or anywhere else) with a flag showing they were invalid I would have noticed my mistake immediately. Anything that alerts the user that the selected item doesn't exist anywhere would be helpful.