Well, I had a similar problem and found that it was just me not knowing how to use the meter
and too lazy to read the manual
. You may try yourself:
If you press METER and then, the softkey for VDC, it only measures from the BNC inputs, but it autoranges to mV.
If you press METER and the softkey for mVDC, it only measures from the banana inputs and it measures up to 3.5V