Just based on the information you have highlighted - I am sure AmEx know you have a high balance on your/their Platinum card, and it didn't stop them from sending you an invite. Depending on the kind of spend, it's perhaps what likely piqued their interest about you. As long as you have a good payment history, personally, I don't see much reason to be overly-concerned. Perhaps settle that bill before you finish the Centurion application, so they know you're good for it.
Best of luck.
/JK
I didn’t even think of that! I’m going to pay it down now before I apply. Thanks for the suggestion. I’ll let you know how it goes with them
