I'm using Creality Slicer, brims and other anti-warming or adhesion settings are all turned off. when I place an object on the bed a shaded area appears around it (See picture).
Is this simply the area in which you can't print anything else in sequential print mode due to the risk of the print head hitting it, or is there some other meaning?
Creality Slicer is a derivate of Cura. As such, all standard Cura things apply.
Your upper surface is denoted as an overhang, this indicates that your item has its surfaces at least partially "upside down". The model needs to be repaired, as such can result in the print solution being "That's to be a closed surface", ignoring the hole in the center. The problem isn't the slicer, it is the generation of the STL that messed up.
About inverted surfaces, see also: here, here and here
The box around parts is also usually created when you try to print multiple items in sequence and relates to the dimensions of your printhead. It pretty much marks the exclusion zone where you are not allowed to place the next item. Check if you have turned print order from all at once to in sequence and adjust as needed.
