In alignment mode, i.e. using maxTxPower the RSSI should be around -50dBm to -55dBm. In Channel 4, the MCS should be 12/11.
So it’s very likely you’ve lost 15dBs and connecting on a side lobe, given that you’re getting 500Mbps with RSSI -65dBm, you’re likely on MCS 4 or lower.
Please take a look at this: 60 GHz cnWave Antenna Alignment