Jump down to skip background info and just get the fix.
Background info:
When I got my A1 printer, in Bambu Studio I could select Textured PEI Plate, Smooth/High Temp Plate, Engineering Plate, Cool Plate, and SuperTack Plate (5 plates usable).
When I got my P2S printer, everything but Cool Plate showed up (4 plates usable).
When I got my A1 mini, both Cool Plate and Engineering Plate were missing (3 plates usable).
I have a LOT of build plates, and each has different textures, z-offset requirements, and drastically different temperatures. I use all the build plate options for setting temperatures. I may want to print at 35C on my Geco plate, or 45C on my Frostbite plate, or 55C on my Glacier plate, or 65C on my Textured PEI plate. If Bambu Studio doesn't list at least 4 plates, I'm going to have to manually change temperatures for every print. I have a lot of printers and print a lot of things, so that quickly becomes a pain.
Every filament profile has temperature settings for 5 build plates and you can set the z-offset for 5 build plates. When the UI only lets me pick from just 3 build plates, that artificially limits what I can do.
Basically, open the printer profile JSON file from your home directory and delete these lines if they exist (not all lines will be in all files):
"image_bed_type": "", "bottom_texture_end_name": "", "not_support_bed_type": "",
Note that if you just delete the "not_support_bed_type" line as some have suggested, the graphics for the "restored" build plate will not show up and may cause unexpected behavior in Bambu Studio. Deleting the other lines will cause Bambu Studio to default to the standard 256x256 build plate graphic for all plates, but they will at least show up.
A list of files with restrictions:
Bambu Lab A1 mini.json Bambu Lab A2L.json Bambu Lab H2C.json Bambu Lab H2D Pro.json Bambu Lab H2D.json Bambu Lab H2S.json Bambu Lab P2S.json Bambu Lab X2D.json
On macOS the files are in:
~/Library/Application Support/BambuStudio/system/BBL/machine
On Windows the files are in:
%APPDATA%\BambuStudio\system\BBL\machine
On Linux the files are in:
~/.config/BambuStudio/system/BBL/machine