Centre tank pump switches
Your right about the low pressure lights, both on to get the master caution.But if one comes on first as it usually does, (standpipes) you'ill get the master caution on pressing "recall"
However if for some reason you select one centre tank pump switch on (mel perhaps) and there is fuel,(low pressure light out) You will get the master caution and fuel light on pressing "recall". This is the only time,that i can think of, you'ill get something on the master caution and not have an amber light illuminated on the overhead.
This was the case on the 2,3,4,500.anyway.
Try it next time you've fuel in the centre. Usual caveats about use of centre tank pumps.