Error using sprintf :Function is not defined for 'cell' inputs.

I am trying to use the Pixhawk PSP and getting this error:

>> PixhawkPSP('/media/user/Extra/MatSimFirmware')
Found compatible version R2017b
Using Target Package path of /media/user/Extra/MatSimFirmware
Error using sprintf
Function is not defined for 'cell' inputs.

Error in codertarget.pixhawk.Px4PSP_Install_UI/build_firmware_callback
 
Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback (line 309)
Error while evaluating Button PrivateButtonPushedFcn.

This was meant to build the PX4 Firmware for me. I'm using Matlab R2017b on Ubuntu 18.06.