The Congressional Record of those days shows that they were talking about the vote. But knowing full well of the existence of the Security Council vote of 20 July 2015, on Obama's Iran nuclear deal – officially designated by the Security Council (SC) as United Nations Security Council Resolution 2231 – the 114th Congress decided not to vote on it.
Houses of the 114th Congress were scheduled to vote to approve or disapprove Obama's arrangement with Iran on 10 and 11 Sept 2015. Congress, earlier claiming concern over the prospect of Iran's acquiring nuclear weapons capacity, had insisted on voting on whatever it was that Obama had arranged with Iran.
Congress had had plenty of time since the 20 July 2015 SC vote to look at the Security Council resolution and the weapons deals contained therein, as well as the permission granted Iran to engage in "activities which could contribute to a nuclear explosive device" as of 16 Oct.
On 10 and 11 Sept 2015 the Congress which had expressed such concern over halting Iran potential nuclear weapons development decided not to vote on the SC resolution which everyone knew about and which sets out how the US and other Parties to the Iran agreement would proceed to assist Iranian gaining nuclear weapons capacity. The Congress decided to vote on only one part of Obama's Resolution 2231 (and didn't approve that). By passing over voting on the entire SC resolution, the 114th Congress decided it would not publicly, on the Congressional Record, openly discuss the extent of the real weapons concessions Obama had made to Iran in violation of treaty. And neither the 115th nor the 116th Congress has discussed these ever since.
There is no question that the US pledge of assistance to Iranian development of nuclear weapons capacity made in Resolution 2231 allows for domestic arms manufacturing and speculative interests to profit greatly from engaging in contraband arms trafficking with Iran; just there is no question that implementation of the pledge violates international law and treaty. Here then, US arms dealing interests were given priority over the rule of law.
The 114th U.S. Congress could have voted on the resolution, along with the weapons concessions included; and decided the US would not support the SC resolution in that the resolution is not in accordance to the Charter of the United Nations, how that works is explained in this writing; and Congressional disproval of Resolution 2231 on the grounds mentioned would have put a very public international halt on implementation of the weapons trading prescribed in Resolution 2231. The system of Charter of the United Nations checks and balances protections against usurpation of authority provides for more than one way to halt a SC resolution other than the better known "Veto;" and despite false rumor a SC resolution is not international law; it's not enforceable unless the Court rules that it is, as will be examined.
In deference to arms profiteering interests; still no public mention in mid 2019 is made in Congress as to international assistance in developing Iranian nuclear weapons capacity. The 2020 Democratic platform campaigns that: "We support the nuclear agreement with Iran because, as it is vigorously enforced and implemented, it verifiably cuts off all of Iran’s pathways to a bomb without resorting to war." Not only are the weapons sales not being discussed, what's also not discussed is that these unmentionable weapons transactions with Iran are contrived to go on in perpetuity. The Party wants back in the 2020 Presidency clearly to serve US contraband arms racketeering interests which it won't talk about.
That malfeasance addressed, this writing clarifies underlying legal points which make it impossible for the Court not to throw Resolution 2231 out entirely – and exposes many false premises imposed on the public by those favoring U.S. involvement in assisting Iran in developing nuclear weapons capabilities.