This seems to be a problem of reading a mat file of an already generated channel trace when using the LTE_sim_main_launcher_demo_RRH.m launcher file. First I can see that you were able to simulate the scenario with RRH, so there is no error in the simulator. When you simulate, it is possible to store channel traces which are saved in data_files/channel_traces. I reccomend to delete the mat file as it might be corrupted and run a new simulation.
If you want in each simulation to generate a new channel trace, that use LTE_config.recalculate_fast_fading = true; in the laucher file.