ADM8324 Reset output stuck at 0 V


I'm having some problems with ADM8324 (complete P/N: ADM8324WCA29ARJZR7).

The IC works as expected but, once in a while, if I switch off and on very fast my power source (in particular if the power supply voltage is above 42 V), it seems like it doesn't start-up (the reset output is stuck at 0 V).

The IC supply voltage is 3.3 V and is generated from a buck converter which takes its input voltage from the power source (DC_BUS).

The IC is connected as indicated in the figure below:

To be sure that this behaviour was not related to other components' failure, I've made some tests even with the MR pin of the flip-flop disconnected from the ADM8324 (output floating, connected only to the pull-up resistor).

The result is the following:

As you can see, in the first part, the IC works correctly (no WD feed, periodic reset pulses), then, after the restart, the output is stuck at 0 V.

How this issue can be explained?