HRM 600 SSL and Fenix 8

Hi, I own a Fenix 8 for a while and decided to try the HRM 600 to get the new advanced metrics as SSL and Running Economy.

What I have found is that I can get some of the metrics, like the GCT balance but the SSL is not working at all.

I have tried pairing the band with the watch with the two blinks option, that should be the BLE and with the three blinks option that should be the ANT+.

Name changes HRM 600 for the BLE one and HRM600:XXXXXX and connection too, but in none of them I can get the SSL when starting a running activity

Any idea of what can be wrong?