Your '.k-scheduler-header-wrap .k-scheduler-header' and your '.k-scheduler-content .k-scheduler-table' seemed to have a width of 178%. This is going to push them out of view. I am not sure if it is doing this automatically, or you are messing with their widths somewhere in your code. This seems to be why the last few columns are hidden.
You also have:
This is going to prevent people from scrolling over to see the rest of the cut off columns. overflow-x should be auto.