Top/bottom of the build plate has grey bars - Ender 3

[Deutherius 0]

Since updating from Cura 4.4.1 to 4.6, there are greyed-out bars at the top and bottom of the build plate for my Ender 3 where no objects can be sliced. I can only assume these are there to protect binder clips, which are generally placed in these positions, since the Ender 3 pro doesn't have those bars (magnetic bed). I cannot for the life of me find the option to enable/disable this feature, or to set the size of these bars, anywhere within the machine settings. Am I missing something, or is this hardcoded to the Ender 3 preset?

 

To be absolutely clear, I am not talking about the grey bars that appear when skirt/brim/raft is used.