i had a bad time with those switches shutting down the product i was shipping,
it is very similar to thermal runaway in a transistor, in fact, that is about the same mechanism they use to make those things,
you can put an ammeter in series with the switch and watch the current sloooooowly creep down, then it creeps down faster, and then real fast till it gets warm, the I^2R losses will then hold the switch off, till what ever it is fusing is either turned off, or blows up, which is unlikely since the circuit is now current limited.
so yeah, i went back and forth with digikey on this till i got something that would work, the tolerances on those things are pretty loose, so you have to protect against the occasional lemon.
and they do not like high voltage, if they shut down across a lot of volts, they tend to explode like a tant cap hooked up backwards,