Following Ubiquiti’s documentation is tricky as it currently refers to EdgeOS 1.7 and with EdgeOS 1.8 we received a new version of Strong Swan which deprecates the show vpn ike sa command.
I discovered this via a Ubiquiti forums thread. I thought it worth repeating as mentioned in there that Edgeos 1.8 the command show vpn ipsec sa now includes any information the deprecated show vpn ike sa provided.