Had a capped Resurrection spell running for 10 minutes and didn't learn a single tick of utility.
Had a capped Revelation spell running for 10 minutes and didn't learn a single tick of utility or augmentation.

Now, Ghost Shroud worked for me. At 30/40 mana, I got the first tick of warding at about a minute in, and up to 22/34 warding in about 8 minutes before it stopped teaching.

I think I figured it out. Revelation's DISCERN says: "To begin to be able to cast this spell, you will need to reach the rank of a beginning aficionado. By the time you have mastered this spell, you will be ranked as a venerated savant in your abilities as a caster."

Savant-dom ends at 799 ranks, so being over 800 ranks means it's not teaching anymore.

Resurrection, likewise, says you'll have mastered it as a Master (899 ranks). Ghost Shroud says it teaches to "guru" level (1249 ranks).

So that is likely the "systemic" issue, but it definitely needs to be addressed so it can be used to teach at least something.