Hi David,
It might be worth updating to the latest version of the utag.js, as there were some IE optimisations in the newer releases of the utag.js. This post should help you if you're not sure what to do:
https://community.tealiumiq.com/posts/762863
If that doesn't work, make sure there are no JavaScript errors in any of your extensions. It's possible that you're using a method that is not supported in IE, and if that's the case, it might stop the tag from firing.
Craig.
Check out our new Swift integration library for iOS, macOS, tvOS and watchOS: https://github.com/Tealium/tealium-swift with updated
documentation https://community.tealiumiq.com/t5/Swift/tkb-p/swift.