50ft flatcar PRR <kuid2:58422:1005:3> will also work. The IM Hub works only with Trailers HP <kuid2:46162:60007:..>. Latest build is :10, 2.9.
I have not found any besides these and the BNSF that Mike cites. One can insert them in the queues in Surveyor but the attachment points are almost always wrong in my experience.
I didn't realize the Hub was broken, but I haven't tried it in T:ANE. It is noticeable in T:ANE that AI trains do not stop where they should, a lesser problem in 12. Of course, if you're driving you should be able to position the flats correctly...
:B~)