As it is today \Drupal\commerce_recurring::refreshOrder() assumes that if no payment method is set on the Subscription, then it should NULL the billing_profile on the recurring order. This causes issues if the subscription type attaches a billing_profile (in the case of invoiced subscriptions).
Instead of defaulting to NULL let's just default back to the $order->getBillingProfile() instead.
Fixed
1.0
Code
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Issue #3322603 by grndlvl: Do not set billing_profile to NULL instead...
Automatically closed - issue fixed for 2 weeks with no activity.