SimpleRTK2B heading with position corrections from base station

I have configured a SimpleRTK2B + SimpleRTK2Blite heading setup using firmware version 1.30 and the corresponding 1 Hz configuration files for the heading kit. I am also using a SimpleRTK2B board as a base station for position corrections. I am able to get heading readouts in u-center through the RELPOSNED message, and I can get absolute GPS position from the SimpleRTK2Blite board, but it stays as “3D Fix” instead of “Float” or “Fixed” mode, and it does not seem to be using any of the corrections from the base station. How can I get absolute position from the heading kit while making use of base station corrections?