Perhaps try cleaning with the tool built into IE and/or Disk Cleanup in Windows, and then return to CCleaner and see if it detects anything different after that.
I use FF exclusively and I have some IE temp interner files also. Try looking at the expanded list and right clicking on one and select Open Containing Folder, and you should see the files.
I don't bother about these, CC cleans them. It's just the way that Windows works, in mysterious ways one could say.
One thing though is the folder path you listed in your first post "T:\Ietemp" is a non-default path. By default IE stores Temporary Internet Files in your user profile. Only noteworthy because in the past like many, many years ago moving where it stores files had the potential of possibly causing issues.