The game itself does not seem to store scribing combinations exactly like it does with traditional skills and their morphs. That might be playing a role here.

Non-scribed skills have distinct skillIDs for the base form and each morph:

Puncturing Strikes is 26114
Puncturing Sweeps is 26797
Biting Jabs is 26792

There's a direct one-to-one relationship between each form of the skill and its ID: 26792 is always Biting Jabs, never anything else. (Unless I've made a typo somewhere, in which case insert the proper ID.)

Scribed skills also use skillIDs, but apparently not in this one-to-one relationship.

Take Wield Soul, for example. Based on what I can see in CMX, some of its forms have distinct skillIDs. These IDs change depending on the Focus script:

Healing Soul is 216813
Leashing Soul is 217784
Warding Soul is 216802
Sundering Soul is 219780
Dazing Soul is 221930

But these numbers don't change based on the presence or choice of Affix or Signature scripts, so how would you know from 221930 what the full combination is? I'm not sure how the game is storing that information, but it doesn't seem to be via the skillID.

And then there's Chilling, Magical, and Shocking Soul. These three get confused in CMX. The add-on frequently shows the wrong name in the log for the form used during the test, and when I relog to get the name to show up correctly, I am seeing the same skillID listed for each one: 215731.

It isn't only Wield Soul that has this issue. Doing a test with Chilling Explosion and then rescribing it to do shock damage (which should be called Shocking Explosion) results in a test where the skill is still called Chilling Explosion in CMX but does shock damage (as indicated by the color of the skill):



Re-scribe it to fire, and "Chilling Explosion" does flame damage:



When it is set back to frost damage, the name is displayed in blue, like this:



Issues with properly recalling and displaying scribed skills aren't limited to add-ons. I have also seen the native game UI itself display incorrect information after I re-scribed a skill. When I was testing Trample the other week, I re-scribed it and immediately checked my skill menu. It showed the outdated form instead of the new one. I got very worried that the rescribing hadn't actually been successful, despite taking my ink. The new form of the skill performed correctly, so it was a problem with display/UI, but it seemed to be a native game problem. In between tests I kept checking, and the issue lasted long enough for me to finish my testing, which was at least ten minutes, so it was not just a momentary glitch.

I imagine only ZOS knows how much work it would require to get scribed skills to register properly for the Armory - perhaps it's something they'd consider working on implementing down the line like they did with Mundus stones - but it doesn't seem as straightforward as other skills, so I'm not surprised this support wasn't included initially.