The headlines cite Iran's deputy secretary to the national security council in saying that "all of Iran's frozen assets must be released and returned without conditions". Adding that they are "seeking the release of all funds held by the US and this is the legal right of Iran".
As mentioned here, this is one of the supposed preconditions that the US is trying to push for in agreeing to the memorandum of understanding. The US wants Iran to fulfill obligations on dismantling its nuclear programme and make deliver on promises before actually lifting any sanctions and freeing up any frozen funds.
However, Iran wants the opposite of that in a move that reflects something similar to the 2015 JCPOA. That being they want the US to lift sanctions and allow access to these frozen funds before or while they are working to "surrender" on nuclear arrangements. But as we've seen before this, the motive by Iran is mostly to just buy time and delay for as much as they can in order to get what they want without actually doing anything on the nuclear front.
So, US president Trump wants to draw a hard line on that. But if Iran also will not budge and wants the US to blink first, how will both sides resolve this issue?
If one piece of the puzzle doesn't fit, the whole picture cannot be completed. In other words, no deal can be struck if even just one precondition cannot be satisfied. And that's where it seems like both sides are stuck right now despite all the talk of an "imminent" agreement to sign off on the memorandum of understanding.
This is just one part of four major key preconditions that needs to be settled. And nothing can be agreed until everything is agreed essentially.
