Here are the issues I came across with induction type sensors:
The induction sensor is triggered by the proximity to the aluminum bed. Whenever you have something else on top the print bed, your print head is further away from the actual metal, and so is the sensor, which obviously can't be set any lower than the print nozzle.
The sensors used for bed leveling are usually low cost tube type inductors with a short sensing distance (4-6mm). So if you have something on top of your printbed, like thick glass, mirrors, PEI, etc, the distance between the sensor and the metal increases and as it gets near the maximum of the range, the sensor becomes more erratic which sometimes leads to a head crash into the print surface.
At this time your solution would be to get a sensor with a longer sensing range (10-12mm), and preferably a better quality one, and you quickly find that the $5-6 sensors don't cut it, and you have to spend around $25-30 for a decent sensor.
Well, that's all cut and dry... until you add a PCB heater like I have. I have a PCB heater on top of print bed, and it has 3mm glass on top of it. The minimum distance from my print nozzle to the metal print bed is actually 6.5-7mm. That forced me to get a sensor that supported at least 10mm.
Anyway, when I first tried it, it worked great, until I turned on the bed heater, and found that the sensor was very susceptible to electromagnetic fields. Whenever the PCB bed power was on, it would scramble the sensor. I don't remember if it was triggering to high, or too low, but suffice it to say, after a lot of trial and error, and way too much trouble that it was worth, I just took the stuff off, and went back to the original switch.
I still have the sensor on my Pritrbot Simple, but it's not in use, it too uses a standard switch, and manual levelling.
To print or, 3D print, that is the question...
SD3 printer w/too many mods, Printrbot Simple Maker Ed., FormLabs Form 1+
AnyCubic Photon, Shining 3D EinScan-S & Atlas 3D scanners...
...and too much time on my hands.