award ticket change fee dropped?

I made a change to an award ticket on Jan 19, 2020 where I should be charged for $50 each person

after the change made, I saw the pending charge on my amex card, but it was pending there for about 3 days before it was gone

I called UA, and I was told the new ticket was confirmed but they could NOT see the change fee charge, and I even got the difference of tax/fee refunded back

Amex told me UA has 6 weeks to "claim" an authorized transaction, but I want to figure this out ASAP so I can use my Amex airline incidental credit better

thanks