Mean Well power supply gives wrong voltage output?
Pin 1 is on the right side of the connector which is a bit unusual, and from the pictures I guess you thought pin 1 was on the other side, so that explains the wrong polarity.



The power supply has a minimum load on two channels, notice it says "0.4-5A" on channel 1, not "0-5A". This is common on this type of switching supplies.



It only has feedback (and thus regulation) on +5V output, so the other outputs will be less accurate, especially if the minimum load requirement is not met.



So you need to make sure your load draws the minimum load current if you need accurate output voltage. Probing the supply unloaded (as in the pictures) will result in too high voltage.