Thank you for your answer, Donna! I actually believe it was a coding issue
Yoast was coding the descriptions as meta property="og:description" only. It looks like Moz and many other tools only consider meta name="description" as the proper code (even if og:description was included).
If anyone else is having a similar issue, what I had my team do is make sure to amend the autofilled snippets descriptions provided by Yoast (which they should have been doing anyways). Editing the autofilled descriptions adds the meta name="description" HTML needed. No more missing meta description errors!