CHW-4403 BillingCycleNotAvailable

the selected plan is not available on the requested billing cycle; pick a different cycle or contact support

Default message: the selected plan is not available on the requested billing cycle; pick a different cycle or contact support
HTTP status: 400 (client)

Problem. The selected plan + cycle combination has no Paddle price configured. Cause. Only one cycle of a plan may be seeded (e.g. annual-only, or monthly-only); the other returns a 400 rather than crashing the checkout flow. Fix. Pick the other cycle, or ask an operator to configure the missing Paddle price. HTTP 400.