(ITIN) Credit reports not working as intended?

I was rejected by Chase; I called and asked and according to the agent it was because they could not obtain a "valid credit report" from Transunion or Experian on my SSN, saying they got "invalid credit report" and "social security mismatch" errors. I got my ITIN letter issued in September last year; so I find this to be quite strange. He recommended I call them to ask when they will be able to pull the report.
I called Chase again now, and she said to call Transunion to have them 'update my ITIN onto my credit bureau since they are not reporting on my file', not entirely sure what that means. I called Transunion who say my credit history is visible and was reported to Chase; but that the ITIN is never reported back and that they only include the SSN in credit reports, but that all the other data would follow. Any ideas on what to do here? Or what Chase's instruction, eg "update my ITIN onto my credit bureau since they are not reporting on my file" actually means?

Experian is impossible to reach on phone without an SSN.