I've only had my box for a day & still have v11.3.3 installed, but I had the same problem. I thought it was a problem with my new provider, but I edited the EPG mode from "Default" to "Alternate" & I got full EPG.
Content Manager > Content sources > Edit > Change EPG mode from "Default" to "Alternate".
aaaah that may be the answer! I have done the clear and update thing two or three times and it didnt change much. Will give this a try!
UPDATE: This worked and its never been this good before!!! Thanks !!!