Regarding CG/L, I am flummoxed that a top ranked US singles gal on the Senior level at one point this decade struggles so much with a 3L, something she used to tack on to the back of a 3Z at her best. I wonder if the 3T would work better
Maybe you are just pointing this out for conversational purposes, but I think the main takeaway is, neither you nor I are champion pairs figure skating athletes, so we have no direct experience. We are armchair observers.
Perhaps Ashley and her coaches could explain why you shouldn't be so flummoxed.
Off the top of my head, I would say that the 3-loop is an extremely difficult jump in figure skating, which some athletes find harder to master than others, since it's an edge jump that requires a great deal of precision, timing and rhythm on takeoff.
I believe that the 3-loop has been a fairly consistent jump for both Ashley & Timothy ever since they competed in singles, and that's why they perform them as pairs partners. Not a lot of pairs skaters have 3-loops in their arsenal. But simply having mastered 3-loops as single competitors doesn't make 3-loops easy jumps to accomplish perfectly every time out. Not even tennis players are perfect every time with their shot-making technique. As with any sport, so many physical and mental variables are involved, not to mention equipment and ice surface variances.
My impression is that simply having been able to land a 3-loop more cleanly as a singles competitor does not mean that consistency can automatically be transferred to pairs skating, which is a completely different discipline on so many levels. There are pyschological and physical factors that will surely vary. For e.g., both male and female pairs skaters (but especially males) have to bulk up a bit to complete the extraordinary athletic feats we see in pairs skating. Therefore, if muscle mass is different, that is surely going to affect jump technique. Also as a pairs skater, you have to jump in sync with your partner which affects timing and rhythm, as well as mental focus.
ETA:
I had posted my above response prior to noticing that
@Cleo1782 already addressed your comment olympic. I remember the commentators saying that Ash/Timothy had replaced their sbs 3-loops with 3-sals, but I forgot that it was in the sp where they took out the 3-loops. In the fp, Ash was surely still recovering from having fallen on the same throw as in the sp, because she was probably thinking too much about not falling again. If you are thinking about not falling, guess what's bound to happen...
Ash was apparently struggling to re-focus when the sbs 3-loops had to be completed in the fp. It's always difficult after making a mistake, to put it aside and quickly regroup. I hope a pairs team will one day write a book about what happens in their heads during a perfect program vs what happens in their heads during an out-of-control, unraveling performance. At 2019 U.S. Nats (which seems ages ago), Ash & Timothy skated last, and they calmly and confidently were able to take each element in stride with muscle memory taking over, which put them in-the-zone. Trying to recreate such calm and confidence every time out is part of what makes figure skating so difficult. To reach for perfection is why figure skaters train their programs day-in and day-out.
As do we all at times. 
Haven is another example of great determination and courage, with her partner Brandon solidly backing her up every step of the way. Josh & Jessica are great examples of dedication and perseverance through injuries and setbacks, as are Tarah & Danny. Alexa is another great example of a nearly impossible comeback story, with her husband and partner Chris by her side as her rock and her lifeline. Coming back to figure skating after the life-threatening crisis the Knierims went through took courage that only they together can understand. Sometimes, there are no words. I thank all of our amazing U.S. pairs teams and all skating athletes for telling us their stories through the journeys they are building on the ice.
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All D/F and C/J need (and granted it's a tall order) are confidence and consistency on their sbs jumps. And as with every team, continued overall growth and rep-building experience. Of course, A&T and the Knierims are currently top U.S. favorites, albeit anything can and usually does happen at U.S. Nationals. But let's keep in mind that what happens during the season factors into World team selection.
