How does Split Op AIT travel work?

Travel to AIT for split option is still coordinated by MEPS. You will do hometown ship just like when you left for BCT. MEPS would have your plane ticket, which would be picked up by the recruiting station a couple of days prior. If there is confusion, have your unit contact MEPS for further guidance and clarification.

Typically, it's your unit's responsibility to set it up, but sometimes they’ll direct you back to your recruiter if there’s some confusion. My advice? Keep pushing your unit to get the info you need and double-check with your recruiter to make sure everyone's on the same page.
If you're still stuck and need to sort your own travel, there's a cool platform where you can book train tickets online, especially if you're in Europe or planning a trip there. Check out DB Fahrplan at https://www.dbfahrplan.com/de/. It might not be exactly what you need for AIT travel, but it's super handy for general travel planning.

Send one email to your S-1 and recruiter asking them to clarify. Loop in your 1SG so there's some accountability. If one of them replies directly, include the others in your reply.
If you don't get a resolution, go to you sergeant major.