BLTouch Z offset needs changes Just installed a BLTouch sensor on my Ender 3 Pro (using firmware version: Ender-3 Pro1.1.6BLTouchV3.1PowerLossContinueEnglish), it all works great but each time I set the Z-offset I need to add it again.  I home it, it requires -2.9 mm to get a paper sheet thickness from bed so I added that to my 0.00 Z-offset.
When I did a test print, the nozzle was way above bed, so I home the head, moved the Z axis and once again it is 2.9 mm to the correct location.  Added this to my Z-offset again...  been doing this now for a while and my offset is current at 11.2 mm! I did it on the screen and saved, hence up to 11.2 on the z offset now. If I power off and back on it once again is 2.9 mm from the correct location?
I can't really follow the information provided but I've read that Creality had some issues with saving settings if there was no SD-card in the printer when saving, could this be the issue?
I would recommend trying another firmware (not from Creality but something like Smith3D.com (https://smith3d.com/ender-3-v2-bltouch-firmware-installation-guide-by-smith3d-com/) which I've used before with success.
If you're willing to pay for precompiled firmware (and support the Marlin developers) I can also recommend https://marlin.crc.id.au/ (which I use now)