I know a lot of people don't want this to be true, but it definitely smells like the truth to me.
Dome and Morrison have continually said that they have had discussions with group(s) in the past (that they only talked about after they couldn't keep quiet any longer) but they had gone nowhere and nothing was in the pipeline as of two weeks ago. However, they also kept saying that they were keeping their options open and that an independent A-League was pretty much necessary for the club to exist long-term. That sounds like a group willing to sell. They have also kept stringing out the process of hiring a new coach (which I'm sure a 50% stakeholder would want a say in) and signing players (ditto).
I know that there are questions about why they would keep the alleged negotiations quiet and ostensibly lie, but I think that is easily explained by a couple of things, first, businesses generally aren't going to talk about this sort of thing publicly if at all possible because it can endanger the deal. Second, this is a really controversial move that pretty much signals the end of the Phoenix, there is no way they would have wanted fans to know until it was a done deal.
TLDR: Welnix have decided to cut their losses for the right offer and kept quiet about it because why on earth would they have gone public with such a sensitive issue?