I’ve had this come up a few times in the past, and usually a reboot of the computer fixes the problem.
On the other hand, while version 2.20 is supposed to be the last version to support the Form 1, I had problems with it seeing the printer sometimes, and I went back to v2.19.3, which is what I currently use.
Try that version first. @MattiaMercante keeps a repository of all the previous Preform versions. You can download it here: