Can't combine pdf page files into a pdf Binder.

Originally, part of the problem we´re discussing was in Photoshop. PS is currently unable to add the dot-file-format identifier that usually follows a file name, e.g., Gobbledigook.tif or Gobbledigook.jpg. When I realized that Photoshop was consistently NOT doing that for my files going into Acrobat, I added them myself (against objections from Photoshop), and it worked. At least Acrobat didn´t complain about the files, but it still wouldn´t do its job.  The PS problem is "a known issue", meaning, I suppose, that Adobe is trying to fix it. I haven´t found an announcement yet that Acrobat´s inability to make a combined pdf is "a known issue", and I´m not certain whether that would be good or bad. I just want to get it fixed. I can add that I´m not running in Catalina, Big Sur, or Monterey. I´m running Mojave and getting the same Photoshop problem.