Got it to work for me.
Steps I did:
Selected a lesser amount ($50 USD)
Logged into Paypal prior to starting the transaction.
It completed.
Maybe it’s the $100 value that’s throwing things off with the strong USD hitting a currency ceiling?
This worked for me after 3 days of trying to buy gems. I sent a ticket into support yesterday but have not heard back from them after they said they would look into my purchase attempts.