Ok, if the three switches are ok next step is to make sure you have the right configuration. Did you go in Settings, select your machine size (XL) and the Z-axis option matching your machine, and then click “Send configuration Data” ?
Now this statement of yours make me wonder:
The “homing” itself happens at the back right corner. Does that work ? Make sure you have “BitSetter” Enabled option UNCHECKED in the Settings page while troubleshooting this.
What did you mean by “home at the front of the machine” ?