I have the same Problem, using Firmware 0.92.9. The 1.0.x are to big for the ANet 1.0 board, maybe if i disable things like LCD Display...but then the firmware is near useless. I have only 3kb to less, but no idea, what more i can drop.
I have MIN Z Stop switch and NPN Sensor parallel on same input pin….but this is ok and work. Merlin can use it, so wiring must be right.
Ok, back to 0.92.9:
Homing work fine, if FEATURE_Z_PROBE is disabled, so i think about where must be the mistake and drink two coffee.
Then i set Z_PROBE_PIN 10, is useless on this Board...but Z Homing work again. So the way to found this Bug is that for Z Probe and for Z Homing on ANet 1.0 is using the same Input Pin. And as ebuyum say, this happens in 1.0.2 too...one day we found the reason and can hope for a bugfix on 0.92.x :) <a></a>
I want use repetier firmware with auto bed leveling, i hope i can found the mistake or a workaround self. Without have reading and unterstand the source, i should check at first the interrupts routine and global variable, there should be hide our trouble.
Sry for bad english, i think german and try to translate in english.