Sorry for the radio silence here.
The rover icon is not showing on the map because it fails to calculate its position. Based on your screenshot, it looks like the corrections from the base are not going through.
Could you please paste here the Simple System Report of your base and rover?
We’ve also written a support tip on how to configure LoRa for RTK on Reach RS2+/RS3. Have you had the chance to check them out? Does the issue persist despite following the recommended settings for your base and rover?