This is probably obvious, but just to be sure…
Some three ways, especially older ones, allow each of the switches to control current to the switch which leads to situations where sometimes turning Switch A up turns on the light and sometimes turning Switch A down turns on the light, all depending on the positions of switches B and C.
That’s when a temporary switch guard is very useful, because you can lock switches B and C into the positions you need so that the unlocked Switch A (in your case, the networked switch) works as you want.
In most newer configurations, though, only the Master switch controls the current to the light. The other switches on the 3 way are “auxiliaries” or auxes, who send messages to the Master switch requesting an on or off. These don’t have to be networked: the “message” can just be current sent directly between the Aux and the Master along a " traveler" wire.
The point here is that if you replaced an Aux with a networked Master switch, you probably can’t turn the light on and off from it, because that point on the wall isn’t set up to control the light anyway. Just to communicate with some other switch which is the real Master. If that’s the case, the switch guards won’t make any difference.
Note that in this second case the LED status light on the switch may be on and the networked switch may be receiving the “on” command just fine–but if it’s not actually wired to control the load to the light, the light won’t change.
Three ways can be wired any of about 8 different ways. So in order to switch from not networked to networked it’s not just a matter of replacing a switch. You have to know how the control wiring is set up and then put in switches to give you the functionality you want to end up with.
So the switch guards are only useful if there is some current configuration where the networked switch does correctly control load to the fixture. If there’s no switch configuration where that happens, you have to back up and figure out which nonnetworked switch controls the load and start from that.