“Hide From Missing Comics” is off (I didn’t even know that was an option). I tried toggling it on and then back off, but same problem.
The “CLZ series ID” for “Harley Quinn, Vol 2” is 52053.
Related to my other post: Harley Quinn Vol 2 #28A, the series ID for “Harley Quinn and Deadshot” is also 52053! I guess that is why they are getting mixed up together. Doing a “Find missing comics” on the “Harley Quinn and Deadshot” series finds all of the comics that are really for “Harley Quinn, Vol 2”, but finding comics for “Harley Quinn, Vol 2” doesn’t find anything.