Code banking in RIDE6

I'm experimenting with code banking. I opened the example project (SPL) and in Options -> Project -> LX51 -> Bank switching -> Modules tab I could see a list of modules, re-assign them to different banks, etc. However, when I create a new project and add SPL_EXT0.C and other files to it and then got LX51 settings and tick the 'Use Bank switching mode' the Modules tab remains empty. After building a project, closing and reopening RIDE it's still the same. Other project settings are RIDE's default. What else may be causing the Modules list to remain empty?

I'm using RIDE 6.10.22, 80C51 ToolChain 6.4.52, MX ToolChain 1.0.11