Starting a new Tier 4 application

[Autke]

Hello All,
Thank you in advance for any help that you can provide. I've been accepted to start a PhD in September, however I won't have results from my MA (which I'm completing under a tier 4 visa in London currently). At first my new university (for the PhD, also in the UK) advised me that I would need to get a letter from my current university that I was highly likely to complete my MA, which I did. They said after I did this, they would be able to issue my CAS so that I could apply from within the country for a new Tier 4 visa.
I've just received a letter from them today stating that because of difficulties with UKIV, they have decided that for students like myself they will no longer issue CAS before results from application from within the country. I can either wait for my results and then they will issue me a CAS, or I can return to the States, make the application, and then come back. They will issue a CAS for this, as applications from overseas are not subject to academic progression rules.
I would rather start my degree in September, and so it sounds like I should return to the US temporarily to do the visa application. I know that the university has said this is an option, but can anyone else verify that this is a legal option. I'm worried that I will return to the states, and my application will be denied because the current visa that I have does not expire until January 2018. I also understand that certain visas have a cooling off period, but would it be right to assume that the Tier 4 visa does not have this? Does anyone have any insight on this?
Thank you!

[sah10406]

I'm worried that I will return to the states, and my application will be denied because the current visa that I have does not expire until January 2018.

That would not happen. Where are you reading that this is an issue? Link?

I also understand that certain visas have a cooling off period, but would it be right to assume that the Tier 4 visa does not have this?

Yes.

[Autke]

I'm worried that I will return to the states, and my application will be denied because the current visa that I have does not expire until January 2018.

That would not happen. Where are you reading that this is an issue? Link?

I also understand that certain visas have a cooling off period, but would it be right to assume that the Tier 4 visa does not have this?

Yes.

I hadn't actually read anywhere that it would happen. I was just checking to make sure that it wasn't an issue. Sorry for the vague phrasing.
Thank you for your help.