Just added a few more credit card providers we found over the last 24 hours to the list for defaulting to SMS due to their apps cancelling payments when using the in-app approvals.
Ultimately, we can try to work around this as much as we can but this is an issue that the credit card providers are going to have to solve before September 2019 when this kind of 3D Secure becomes common as a result of EU regulation on Strong Customer Authentication. 
Having said that, we’re currently discussing how we could further work around this issue under the constraints we have. A lot of the suggested methods wouldn’t satisfy the regulatory or technical requirements we’re under. 