It's my suspicion that the means-testing, or other hurdles, prevent the benefit from being universal, thereby preventing the inflationary effect.

Incidentally, I'm not declaring a belief in either means-tested benefits nor UBI, just exploring the territory.

Yeah, the effect of a windfall on everyone who already had their basic needs covered would cause one-time inflation, but at least it shouldn't be an inflation treadmill of "people get UBI, prices raised to meet that UBI, raise UBI again, prices rise again" any worse than we have already with welfare.

Money is not being created from thin air so why would you think there was inflation?

Actually, it is. States/Central Banks can print money as they wish. Go be more exact: printing isn't even necessary, money nowadays is barely more than a replicated database entry.

But that has nothing to do with UBI. All the UBI schemes proposed get the money through general taxation of some kind.