Few days ago I’ve managed to successfully top up with my MasterCard. Trying again today gives an error saying I need to activate 3DS. So I did - I activated 3DS for this card but the same error message appears again and top up fails. Support seems is not aware of the reason and has no idea how to solve this - they told me 3DS is not supported at all and I should continue trying in both modes (with and without 3DS activated). Ofc, it didnt work. Then I’ve registered another card - VISA - that has 3DS activated. The top up was successful , Revolut app has loaded the verification screen and everything worked fine.
So seems it is now broken for MasterCard only (note again few days ago the same card worked fine).