I was surprised to learn that Revolut is not a reliable card for TfL, unfortunately. Since I haven’t had this problem before, I am still trying to understand the scope of the “problem”.
Last weekend, my card would not work on some gates. I couldn’t check in at King’s Cross, Victoria line and also not at South Kensington, Piccadilly line.
It worked fine on numerous busses, at other tube stations and railway gates.
Support told me that not all gates are online terminals. Is it known which gates are likely to fail?