EDIT: I also submitted a Support Ticket for this, as I'm not sure what the best route was. I'm leaving this post up in case other Tenno have run into similar issues.
As the title states, I recently built, gilded, and mastered a Zaw that used the Mewan strike (along with every other strike besides Sepfahn and the Plague pair), but for some reason, it is the only Zaw strike that does not show as Mastered in my profile. I'm not sure if this is strictly a UI problem or if I am actually missing the Mastery for it, as I get conflicting info from the game depending on where I look.
When I talk to Hok in Cetus and select the Mewan Blueprint, it shows Mastered:
On the other hand, when I look at my profile in game, it does not show as Mastered (last item on the right in the image below):
Has anyone else run into this before? Am I going to be forced to completely re-do this Zaw process, or can this be fixed on the back-end somewhere?