There are a lot more bug fixes but that just aren't player facing issues.
When our QA team is testing a build there could be crashes or a varity of other issues that get fixed for us to put out the patch. These are issues players never run into due to being fixed prior to the release of the update.
So yes, while in the patch notes only 1 issue listed in the update notes, the team is working behind the scenes to fix a variety of issues that players never know exist in the first place.