Read only, immutable, frozen, unchanging, static… just not working! tl;dr: Both the panel and the operator need access to any properties- using a PointerProperty to a PropertyGroup which holds the operator options / properties and is stored somewhere accessible (like bpy.types.WindowManager) is a decent way of doing this (ref). When I went to implement the … Continue reading [solved] Why is my Blender addon panel property read only?