@dmunio Can you check if this is still a problem in the 6.7 branch? The 3d secure for subscription should be working - but the challenge is displayed on the "Thankyou" page instead of the first page in this case.
Also, it is not good if the contribution is showing "Completed"!
@mattwire , On the latest version of stripe (6.7-dev) and mjwshared (1.2.2-dev), I get a javascript error (when using a credit card that requires 3D Secure)
Using the latest stable versions of stripe (6.6.3) and mjwshared (1.2.1), I can confirm the bug reported in this issue.
@mattwire , With the latest version of Stripe (6.7-dev), mjwshared (1.2.2-dev), and contributiontransactlegacy (1.5); when using test card '4000008400001629', the error "Your card was declined" is reported. That is, it works correctly.
But when using valid 3D Secure cards (example: 4000000000003220 or 4000000000003063), the form reports an error: "No such plan: ..."
@dmunio I think this is now fixed with latest contributiontransactlegacy + stripe 6.7 branch.
Please note that all 3 cards will fail for subscriptions with error "Payment failed". 4000000000000341, 4000000000003220, 4000000000003063. This is because they are all test cards which are expected to fail for first payment as they require 3DSecure for every payment. 4000002500003155 will work for subscriptions.
I made a bigger change that should help with getting more "success" from cards which require authentication. Now when we do not know the final amount (eg. multiple event registration) or we are creating a recurring contribution/subscription we will create a "setupIntent" with Stripe on the same form as you enter the card details. This means that the user will get a prompt to do 3DSecure validation when they click "submit" if it is required - previously this was not possible on drupal_webform.