Solution: Use G92 instead of G29.1 for Z offset on A1
After a lot of trial and error, I found that G29.1 commands get ignored/overwritten by G29.4 at the end of the Machine Start G-code.
The fix: Add this line AFTER G29.4 at the very end of your Machine Start G-code:
G92 Z-0.08
Adjust the value to your needs (negative = nozzle moves higher). This redefines the Z position after all calibration is complete so it actually sticks.
If folks want to stick with the Prusa Slicer I found this method actually works to change your z offset. Tooks A LOT of messing around to figure it out though.
**Solution: Use G92 instead of G29.1 for Z offset **
After a lot of trial and error, I found that G29.1 commands get ignored/overwritten possibly by the G29.4 at the end of the Machine Start G-code.
The fix: Add this line AFTER G29.4 at the very end of your Machine Start G-code:
G92 Z-0.08
Adjust the value to your needs (negative = nozzle moves higher). This redefines the Z position after all calibration is complete so it actually sticks.
Hello. I’ve just found this thread as I have the exact same problem. Identical to your photo! It’s driving me mad and so far @BambuLab are not being helpful. Waiting on my next reply.
My first layer adhesion is good (prints do not detach), but I am consistently seeing bad first layers, including blobbing and indents from the nozzle/scrapping against the previous layer. Before I was achieving perfectly smooth and consistent first layers. You could hardly see the lines at all.
To rule out user error, I have carried out the following troubleshooting steps:
• Thoroughly cleaned the build plate using warm water and soap, then air-dried it without touching the surface
• Ensured all filament has been thoroughly dried prior to printing
• Tested multiple PLA filaments
• Increased bed temperature for the first layer
• Reduced first-layer print speed
• Increased first-layer line width
• adjusted filament flow
• Confirmed automatic bed levelling completes successfully before each print
• Repeated multiple test prints of different models to rule out isolated failures
• Tried new build plates and new nozzles
• Completed the flow calibration, and completely recalibrated and reset the machine
• Tightened the hot end screws
In addition, a professional technician has inspected the printer and attempted to resolve the issue. They were unable to identify a slicer or filament-related cause and were also unable to restore the previously successful first-layer results.
The consistent conclusion from testing is that the issue is the Z offset. And it changed from working to not so fast. Like, overnight it felt like. the printer was producing perfect results consistently for 6 months (around 1000 hours of printing) before the sudden change. Location, and other outward factors which could impact the printer have remained the same. There has not been any accidental damage. And I have maintained the printer well, adding lubrication when instructed by the printer.
So the part which needed changing for you was the extruder? Good to know. I hope they come back with a better reply. Despite telling them all the above already in several back and forths, this is still being held as my fault at the moment. 
I want my first layer back! It’s messing with the fine detail and quality of prints, and flat surfaces, and I’m getting elephants foot issues which I never used to get.
Hello, when you said producing perfect results consistently for 6 months, and then suddenly problem, same with me. now after trying everything above i am sure its hardware related.
@DarkDodger Are you sure? In most common 3D printer firmware setups (e.g. Marlin-based systems), a negative Z-offset moves the nozzle closer to the build plate, not farther away. The offset value is applied relative to the probed or defined Z=0 position, so a negative number lowers the nozzle in physical space. A positive Z-offset, conversely, increases the distance between the nozzle and the bed.