NextStep2 regulator bulk charge issue

[jackt]

I recently replaced my 10-yr old NextStep smart regulator with their most recent (mid 2000s) model, NextStep2. (Potentiometer control on old one seemed to die). It does not stay in BULK charge until the set point (14.3 V) with constant amps as it is supposed to, if a fair load has drained the amps, eg, -40 ah used up. Instead alternator puts out about a constant 60 amps with volts increasing as expected, eg, 13.4...13.6...13.8...then when it gets to about 13.9-14.0 V the regulator trips EARLY into ABSORPTION PHASE which means amps decreasing: 60...55...50...But all the while volts are still increasing up to the set point of, eg, 14.3 V. When it gets there, after about 30-40 mins, it does stay there at 14.3 V, while amps continue to decrease for the set time (eg, 1 hour); then it trips to float (sometimes at about 18 amps still going in).
If less amps have been drained, eg, -10 amps, then it ramps up to 14.4 quickly (1-2 mins) and acts as it should, tripping to ABSORPTION (ie, it gets to the set point quickly with constant 60 amps).
BATTS: 4 x 225 ah 6 V deep cycle batts = 450 ah bank.
Alternator: Bosch 85 amp that puts out about 60-65 amps - I know it is under-rated and not the recommended 20-30% of batts size.
Q. Is it to be expected to trip out of BULK *before* the set-point because of my small alternator that can not put out "enough" amps?? So then it sort of fizzles out of puff and trips to ABSORPTION...early?? The manual/leaflet (see link) mentions something along these lines. Has this something to do with "what the batteries can accept" etc and what can be given to them? What does that mean?

https://www.amplepower.com/manuals/ns2/ns2.pdf

"The regulator will not stay in bulk charge mode long if the batteriesare full, or the alternator can produce more than the batteries will
accept.
The regulator cannot drive the battery voltage to any specific level
if the alternator is not capable of producing enough current to
satisfy battery acceptance capability, which varies with state–of–
charge.
Alternators don’t produce maximum output unless they are rotating
at 6000 to 7000 RPM, so don’t expect high current unless the alter-
nator is rotating fast. If the batteries won’t accept high current, the voltage will quickly rise to the absorption setpoint and hold atthat voltage. The regulator hasn’t skipped the bulk charge step, just
moved through it rapidly because the batteries don’t accept much
current."