Switch that Fluke to AC and hang it on the meanwell output while changing the load.
Should still read zero = (no change in DC level.)
Well, it holds 12V DC real well. Adding the 100 ohm resistor jumps the AC reading from 142.8 mV to 152.8 mV. Seems to ramp up nice and smooth, though. Is this acceptable?

No other anomalies noted, but I probably wouldn't know 'em if I saw 'em. A hundredth of a volt seems okay.....