I'm suprised nobody has posted the fix for this, it's a known problem that has been around for ages.
Simply schedule a task to do a re-index of the EPG data after your scheduled import. ICE could add this to their software quite easily.
You can either run the following command
%SystemRoot%\ehome\ehPrivJob.exe /DoReindexSearchRoot
There's also a task in the Task Scheduler Libary on Win7 that's ready to go. It's under
Task Scheduler\Task Scheduler Libary\Microsoft\Windows\Media Center\ called "ReindexSearchRoot". Just change the schedule to run daily or just after your ICE Import.
To the contrary, the software has always executed this task after an EPG load. In fact, a previous beta would also wait for it to finish before scheduling new shows. The success of this task seems to depend on whether Windows Desktop Search is installed, and whether Media Center has registered with WDS.
Sometimes, this task fails, no matter what, and the way around that is to remove WDS from Programs & Features > Add/Remove Windows Components then add it again, followed by running the "RegisterSearch" task.