Rockwell introduced new primitive datatypes in recent firmware versions, including LTIME. If you really need these, you might consider testing my new EtherNet/IP driver, which should support these. It is in beta, and not tested much on these types, but I wouldn't mind a data point:
However, I suspect you aren't actually using these tags (or you'd have found this problem earlier). Which suggests that someone dragged and dropped an entire tag hierarchy from the OPC browser to Ignition's tag browser, creating subscriptions to everything. That is an extremely bad practice.