Same thing is happening to me in PT 12.3 HD… except it’s H910 Dual that disappears inside PT, although it’s in the proper AAX plugin folder.  It loaded fine in the previous version of PT before I did the update, and it was the only plugin that “disappeared” after the update.  I’m on OSX… and the regular 910 shows up and loads, but the H910 dual does not.  I tried re-downloading and re-installing Anthology X, but the problem remained.