For Neptune 4 plus/max, it is recommended to set the first layer thickness to 0.2-0.3mm. To further improve the level effect, please try:
1. The screws at the marked positions ; These screws need to be kept loose
2. The X-axis needs to be parallel to the hot bed
https://www.youtube.com/watch?v=SNqO084jRME
3. Turn off the printer power, and then check whether the pins at the marked positions are deformed or damaged.
4. Check whether the proximity swich plug is damaged or loose；You can refer to the video below for the disassembly steps：
https://youtu.be/z_0IVMnSEN0
After checking the above, please update the latest version of the firmware and switch the level model to professional mode in the settings.
Please note that the firmware of the motherboard and the touch screen are matched and both need to be updated.If the firmware does not match, it will cause the printer to function abnormally. After completing the update, you can check the firmware version in the Touch screen → Settings → About printer. The latest motherboard firmware version is 1.2.2.64 (Neptune 4 plus/ max) and the touch screen firmware version is 1.2.11 (Neptune 4 plus/ max)
Frimware download link:
https://www.elegoo.com/pages/download
PS:
Only the Z offset set at "level" can be saved, and the adjusted Z offset value at other times will be lost after the printer is turned off.