You need at least one of these:
a stiffer input supply, whose load-sag at startup when the
converter hits into it at full load, is less than the UVLO
hysteresis. But the attributes here may be a "given" that
you don't get to constrain to your liking
more UVLO hysteresis, to accommodate the amount of
input load-sag that you are presented with. Here, you
may only be looking at a "present case" and not "worst
case". You need to deal with some range, which may be
unpleasantly wide.
a more leisurely startup, that doesn't try to slew from
no current to full current into the output filter and load
so abruptly. Enforcing a lower output dV/dt or di/dt may
keep you out of motorboating startup mode. Do you have
a "soft start" pin that will let you hang on a capacitor
and lower the startup ramp rate?