I'm only really familiar with Abu Dhabi but there, idleness is a concern.
It's directly evident in schemes such as paying school children to exercise.
However, it is masked somewhat in the adult population as foreign companies are required to employ natives in senior positions. Anecdotally, the incumbents aren't famous for their work ethic.
But it's hard to argue that it's not overall positive for the local population. Healthcare, education, services etc are all excellent.
That being said, I don't think these are useful comparators. The elephant in the room is who is paying? In the case of Abu Dhabi, it's the buyers of their oil. As such, you don't have an internal tension between the net tax consumers and net tax generators. Nor do you have a significant allocation of resource issue when there is a surfeit of resource.
And I think it's the latter issue that is a critical one for UBI.
Although not equivalent, I think the example of UK child benefit is instructive. It was a universal benefit in the sense that it applied to all children regardless of parental income (it differed by birth order but that's not material to the point). While the economy was doing well, the money flowed. Post crash, the economy tightened and it was an immediate target and became means tested.
It's not clear to me that, even if you managed to get UBI implemented, it would be stable. I would expect that it would need to show tangible, widespread benefit in about one economic cycle. Otherwise, as soon as things started to slow, you'd be seeing stories about the wasters and layabouts. It wouldn't matter if there were many cf the refugee "deluge" or similar triggers.
In other words, I can see UBI lasting only if a number of other, very significant economic (cycles) and societal (selfishness) issues are resolved. Tricky.