Hi Dear Jhon,
I'm facing the same issue as you, the 'Display Only' is not set in the GUI, but I can not change the value in the WebUI. I debuged and also get THRRRRR. It reads the third postion, 'R', so I also can not change the value. Could you please let me know how you solved this issue. It confused me all the day. 
Thank you so much.
BR
Jay