There's really no enabling involved; if configured for AHCI, they should both be showing up. If one is not responding, it may be a hardware issue. Swapping the SSDs and seeing the issue remain with the (same) port is a pretty good indication of an issue with the port...
If the place you bought it will swap it for another, you might want to do so. Alternatively, contact Intel Customer Support and talk to them about RMA.
Sorry this happened to you...
Go into the bios and be sure the second m.2 port is enabled. On boot F2, search the menus you'll find it.