I operate a telephony service (perhaps similar to the one you parked your number at) and we do thousands of ports a year from our service to major carriers. Porting is such a backwards pre-internet system and things go wrong all the time unfortunately.
My guess is that the port went through but US Mobile has lost it in their system.
One of the biggest issues I see is when porting from a VoIP service to a carrier. The carrier doesn't always know what to do since it is slightly outside normal; the majority of their customers are moving between major carriers. But now your number has been classified as a "wireline" (VoIP) number and US Mobile is probably confused.
Honestly, I bet it magically arrives at US Mobile after a bit of time. But if you can't wait, I'd engage the VoIP service again. They likely operate downstream from a provider such as Bandwidth, Twilio, or similar. Their team can ask their upstream provider for a "snapback" of the number - essentially they can go take it back. That will leave you with your number back at the VoIP service to try again when you're ready :)
With all that said, I do have access to these upstream systems and some more advanced lookup tools. Shoot me an email (in bio) with your number and I can do some research for you if you want. Good luck!