I'm using octoprint along with the Bed Visualizer plugin and noticed some ABL meshes generated by my CR6-SE would have some very large errors. Plus, I noticed large variation from test to test. To diagnose this problem, I took the print head apart and noticed the blue light would turn on/off when the print head moved back and forth due to the bowden tube putting pressure on the hot end and tripping the load cell. So, I created and printed a bracket that screws onto the printhead and supports the top of the bowden tube to relieve this pressure when it moves back and forth. All of my ABL cycles since this installation has been very consistent and all subsequent prints have beautiful first layers. I'm slicing with Cura 4.7 configured to automatically perform the ABL at the beginning of each print. I've shared the bracket on thingiverse if anyone else would like to print and see if it helps their printer.
https://www.thingiverse.com/thing:4628644

@phamtom009 I'm using Octoprint and Cura 4.7 but I'm able to initial a ABL with the normal G29 command. I'm also able to use the Bed Visualizer plugin to see the mesh generated by the G29 command. Also, there isn't any EEPROM in the CR6 mainboard so it's not capable of storing a ABL mesh. This means you'll need to perform the ABL each time the printer is turned off. I've just setup Cura to initiate an ABL at the beginning of each print to make sure I don't forget to do it after a power cycle.

This sounds like it might be the same problem I had. The bowden tube was putting pressure on the load cell when the print head moved back and forth and caused the ABL to detect incorrect z-offsets in the corners. I printed a bracket to hold the bowden tube at the top of the print head to prevent it from putting pressure on the load cell while it's moving back and forth. The bracket is available here if you'd like to try it.

I'm using octoprint along with the Bed Visualizer plugin and noticed some ABL meshes generated by my CR6-SE would have some very large errors. Plus, I noticed large variation from test to test. To diagnose this problem, I took the print head apart and noticed the blue light would turn on/off when the print head moved back and forth due to the bowden tube putting pressure on the hot end and tripping the load cell. So, I created and printed a bracket that screws onto the printhead and supports the top of the bowden tube to relieve this pressure when it moves back and forth. All of my ABL cycles since this installation has been very consistent and all subsequent prints have beautiful first layers. I'm slicing with Cura 4.7 configured to automatically perform the ABL at the beginning of each print. I've shared the bracket on thingiverse if anyone else would like to print and see if it helps their printer.
https://www.thingiverse.com/thing:4628644