This is a variation of a question that came up often enough. In practice, a chargeback will currently be your only recourse in cases like this.
For obvious reasons, airlines do not want to give refunds currently, and are even pushing for legislation that would allow them to give out vouchers instead of refunds, and delay the actual payout for up to a year.
However, at this time the EU regulation still stands: You are entitled to a refund if your flight is cancelled in all cases - even if the cancellation is not under the airline's control. Nevertheless, the airlines won't pay; and I assume that even if they agree that you are right they may simply try to delay payment until after the crisis.
If they do not refund you, you can request a chargeback. Here's guidance from the ING, one of the large banks in Germany. It's in German, but in a nutshell:
- You have to talk to the company (airline) first
- If they offer a voucher, the bank suggest that you take it
- If you do not want a voucher, you need to request a refund from the company/airline
- If they either refuse, or do not react, or do not refund within 30 days, then you can ask to initiate a chargeback
Best to keep all the documentation of your attempts to resolve the situation (e.g. emails sent).
Note: While the OP has a US card, chargeback rules don't vary wildly and you are entitled to a refund if the other party has no legal right to the payment; also the EU regulations for refunds apply in this case regardless of the nationality of the passenger.
Good for the OP that they got the situation resolved.