Prior to Dev version 26.1 the M2/RS2 could not transmit RTCM message 1008 which trimble components need to get a fix status. They can also go fixed with message 1007.
All the details are in this thread My M2 project, Trimble Base Station
To sum it up, I have an m2 putting out RTCM via serial at 57600, it is connected to an Arduino Nano that is programmed to add a blank message 1008 if there is none present but there is a message 1005/1006. It lets the rest of the RTCM messages pass through and adds the 1008 via serial port at 57600 which is connected to a RFD900+ radio which transmits to a 3DR radio that I have connected to my Trimble monitor for RTCM corrections.