Hi,
It is necessary the error flag clear when the MCU is started/powered up. It is possible that in this case the voltage is evaluated sooner than it is in correct range.
However, if the error appears during running mode then it is necessary to measure conditions by setting voltage trigger at the oscilloscope to be able investigate the reason of the voltage drop.
Moreover, this drop, if during run, should probably also be visible at overcurrent protection.
TO measure VLS_OUT is not enough there must be deeper investigation and measurements.
Best regards,
Ladislav