No, something else is probably your problem here since I can easily go over 500 mA in low (in your case middle) range (current range set to Best/Default, and with Autoranging set to on). Did you try to replace R179 with 0R for test before you put that extra wire?
Sorry to bring it up once more, other builders of r5B13 boards may also run into this issue.
When working with the psu in the 500 mA range it seems not possible to reach the full 500 mA with the r5B13 power board as it is. Somewhere between 460 and 490 mA the CC mode takes over, although the set current limit is 500 mA. Seen this with all four power boards I have tested.
Comparing the r5B13 with the r5B12 power board layout the trace between R63 and R65 is much shorter, see picture r5B12.JPG. Also the shunt resistors are twice the value, halving the relative influence of trace resistance.
I soldered R63 and R65, -A and -B on a spare power board r5B13, picture measureC.JPG. While under a load of 500 mA, in series with an external 4 ohm load resistor, I measured these voltages:
left pad of R63, supply from load resistor : 52 mV
other of pad of R63, trace to R65 : 11 mV
left side of R65, -A and -B : 5 mV
right side of R65, -A and -B ,common : 0 mV
I also measured these voltages on a 'life' power board in the psu while in 500 mA range and under almost 500 mA load. They are about the same.
So there is a 6 mV drop over the trace from R63 to R65, apparently a trace resistance of 0.012 ohm here! Total shunt for 500 mA sums up to 0.104 ohm in stead of 0.092. Compare this to a power board r5B12: R65 is 0.02 and R63 is 0.16 ohm. The trace between adds about 0.006 ohm, being less than half length. That is 3% of the total. The 0.012 ohm trace of the 5B13 board adds 13% to the total shunt resistance for the 500 mA range. So the voltage measured is 13% higher than intended... You can calibrate this away but the set value voltage from the DAC is limited, and so the current can not reach the intended 500 mA in CC mode.
Another thing: 13% of the 500mA shunt is the copper trace with 4000ppm/K Temperature Coefficient, significantly worsening the temperature stability of the 500 mA range.
@ Channel failure after assembly:
With one of my boards I had IC11 swapped, pin 1 to pad 4, that caused -5V rail failure.