Question -

On a well with a rates & reserves multiplier, with an Eclipse forecast, the Max Lift gas rate does not work properly.Why?

The .RSM file input specifies around 780 Mscf/d GL, the rates multiplier is 1.795
So the max GL is around 1400 MSCF/d
But limiting the Max Lift gas rate to 800 Mscf/d does not impact the outputs at all: the resulting GL is still around 1400 MSCF/d
Worse, by setting other lower limits, the software respond by outputting different limits:
Limit GL (Mscf/d)           Result GL (MSCF/d)
0.8                                     1.3
80                                      137
160                                     275
800                                    1344

Answer -

The rate multiplier multiplies all well constraints, including the maximum gas lift, so the numbers are roughly what would be expected. If you want an actual limit of 800 kscf/day, then you will have to input a limit of 800/1.795 = 445.7 kscf/day