What revsion are you running? Using the "Refresh EPG" what I've been doing everytime I test, So not sure whats going wrong.
ATM am running rev 14533, from yesterday...
Don't know why it would not be working for you... make sure you enter the timezone compensation and then try deleting the tvguide.xml file and then clicking the Refresh EPG button to clear the existing programs out of the DB, and then run xmltv/webepg/etc to recreate the tvguide.xml file.
The XMLTV Import plugin applies the timezone compensation as it is importing the file, so just changing the compensation will do nothing, you need to clear the EPG DB (by using the refresh EPG button) and then recreate the tvguide.xml file and let it reimport it....
If that doesn't work, then i'm out of ideas...:sorry: