> What happened?
> Now it appears by most proposals to be yet another means-tested add-on.
"Universal" means not means-tested. That hasn't changed.
What happened is that those who promoted UBI in order to achieve their objective of dismantling the social safety net and reducing overall taxation and government expenditure lost interest in it for many reasons.
First, and most important, the UBI supporting right largely returned to the standard economic platform of the right, since the political changes in 2016 resulted in many of their goals being achieved, including the attacks on Obamacare and food stamp programs, and the massive tax cuts for the very wealthy.
Second, they couldn't really explain UBI to others in the mainstream right. Simply cutting the safety net to punish "lazy" people who leech off the system is, and has always been, an easier line to sell politically vs "we consolidate all the existing safety net expenditures, cut them by x% by dismantling the bureaucracy, and distribute the cash as UBI, for a net reduction in total expenditure". UBI is economics nerd stuff on the right, a clever scheme and experiment whose costs would be ultimately paid by others who were less fortunate - in the form of reduced overall benefits.
Those who were left supporting UBI (no pun intended) were those who see it as one tool among many needed to reduce inequality, not as a way to further reduce government assistance to struggling people. They believe the cost should be payed by greater taxation on the wealthy, and their support is rooted in their beliefs about what a more just society would look like. Their perspective was further bolstered by Andrew Yang's advocacy, and the measures being taken now due to covid19. Therefore their perspectives on UBI have become the dominantly heard perspectives on UBI.