When you have no decryption you need to use layer 2 or layer 3 service and then you can send not decrypted traffic as for http service the SSLO adds a header to track the flow and it can't if it is not decrypting the traffic..
This is the most important distinction between HTTP (proxy) and L3 devices. An L3 device will simply route traffic across its interfaces without manipulating the packet headers. A proxy device, by definition, alters the packets headers. SSL Orchestrator uses the ephemeral packet tuple information to track packets across inline L2 and L3 devices. But as an HTTP proxy device manipulates this information, SSL Orchestrator uses an HTTP header signal across an HTTP proxy device. This signaling mechanism limits an inline HTTP proxy device to unencrypted HTTP traffic.