Your suspicions are correct. I always suggest using my closing attorney for this very reason. Whoever has the deal has the power. Buyers are a dime a dozen - deeply discounted properties are not. Always remember this. If I must use the buyer's title company/closing attorney then I always demand to be on all correspondence between the title company, seller, and buyer. It should raise suspicions as well if you're in an attorney state and he says he's using a title company.
You have to be on the HUD and you should receive it no less than 24 hours from closing. If you are not on the HUD, you will likely not get paid. I would call the title company ASAP and request to speak to a paralegal or closing representative regarding your deal. If you signed the original purchase contract with the seller then you have a legal interest in this property, and they should be corresponding with you every step of the way.
Always, always, ALWAYS make sure you are on the HUD settlement statement. Your assignment fee should appear on lines 1303 or 1304 on the second page.
I have had buyers close deals behind my back and also try to reduce my assignment fees before closing without speaking with me. There are a lot of shady players in this industry, and with the market tightening up, I only anticipate the shadiness to become more prevalent. Protect yourself. You are the only one who is representing yourself in this transaction. At least if you chose the closing attorney/title company, you would be the primary point of contact. However, in this deal, you are akin to the third wheel in a romantic relationship.
There is no need to go into panic mode. But I do suggest having a bit of urgency on this because once the deal is closed, it's done - nothing you can do. You could pursue legal action, but I found that this is more trouble than it's worth and not worth the negative energy surrounding this. It can end up stalling forward progress in your business. Nip this in the bud. Get some clarity. If you do not hear any word from the buyer or title company within 24 business hours, I suggest filing a memorandum of contract to cloud the title. This can be bypassed by savvy attorneys, but at least you will show up on the title for having an interest in the property.
All the best,
C.C. Garland