I'm pretty sure something is wrong with the firmware I downloaded. I flashed the 3/5/21 version of Marlin firmware from https://marlin.crc.id.au/ and it is somehow working better with the LCD firmware (which I got from TH3D), the Z offset is working as it should, and the leveling process has more points and goes faster.
Is it something like in this video?
Extending/retracting when NOT probing works fine, but probing fails with the pin not correctly retracting?
Then the BLtouch is defective and it should be replaced. It is not a firmware issue.
I had the same problem. It seems it was definitely a loose connection on the BLTouch. I put a wire tie around the neck of the BLTouch, just underneath the mounting feet, to secure the wire and ensure a good connection regardless of position. It has worked great so far.
I was wondering if it had something to do with my Z axis and BLTouch. When I unplugged the Z Axis on the printer the extruder wouldn't lower only raise so I plugged it back in and it moves in the right directions. The mother board I'm using is a SKR E3 Mini V2 and the BLTouch is 3.1 On that version motherboard the BLTouch plug has all 5 wires combined in one ...
There are various designs which can be made to work at 100 °C.
For example this solenoid probe uses a solenoid to lift a plunger during print, letting it drop during probing. The design uses a rare earth magnet which usually loses strength at 60-80 °C, but there are high temperature versions or a ferrite magnet will do. It also uses an Attiny13, rated 80 °C, ...
3D printers like the German Reprap (see image) already uses a photosensor for homing the axes. The trick will be leveling the leveling sensors.
However, if you use an optical sensor measuring distance, you could mount it on the hotend like we do digital indicators (drop gauge). See Bed leveling method?
You would want a resolution of about 0.01 mm. That ...
Have you considered using or adapting Prusa’s P.I.N.D.A. V2 or SuperPINDA? Seems that within some bounds they’ve solved the temperature compensation issue.
The older P.I.N.D.A. V1 sensor seems to be temperature-sensitive. See more information in P.I.N.D.A./SuperPINDA Sensor testing article of Pruse Knowledge Base.