Looking for DPs on how AA processes Instant Upgrade refunds when the ticket and upgrade are paid with different cards.

Here’s my situation:

• Main Cabin fare purchased with corporate card.
  
• Instant Upgrade purchased later with personal card.
  
• Might cancel the trip after 24 hours (so outside the full-refund window).
  

AA’s terms say:
“If you cancel after 24 hours, upgrades purchased with a credit or debit card can be refunded to Trip Credit for the value of your upgrade.”
Questions for anyone who’s done this:

1. Does that Trip Credit show up in your AAdvantage account, regardless of which card was used?
   
2. Or does AA ever try to tie the upgrade refund to the ticket’s payment source (corporate card)?
   
3. Any DPs on whether the Trip Credit is cleanly issued and usable like any other?
   

Trying to confirm it’s safe to mix payment methods (corporate for fare, personal for upgrade) without refund complications later.

Thanks in advance — data points appreciated.