Switch Statement Routing to Separate VS Using 'Virtual'

Couple of things. Since you're running iRules on these, I'm assuming that you have an SSL-Client side profile on both the API vip as well as the front end. That being the case, sending to the HTTPS virtual could very well be your problem since you've already decrypted the traffic on the first VIP.

We do this handoff using the virtual comand all the time without issue. Other than the previosly mentioned "return", there's nothing wrong with what you're doing... as long as you're not having to deal with to SSL-CS profiles.