Currently only your "main" PC will show up in the engine room.
This is a known issue.
Space Coin production in parallel
You should be producing Space Coins with all your PCs in parallel, even if they don't show in the Engine Room.
To check whether or not the PCs are individually contributing try to activate them one by one and keep and eye on the Pod Engine Status, specifically the projected Space Coin / day value.
If you continue to experience your issue after following all the steps in this article, please create a Support Request to contact Support.