You must be doing something not quite right. Try this:
- Start a new project, and add a player holding an instrument.
- In Write mode, select the first rest in the instrument’s staff.
- In the Key Signatures panel on the right-hand side, choose 24-EDO from the tonality system drop-down.
- Type Shift+K, and in the popover type “atonal”, then hit Return.
Now you should have the score set up properly for 24-EDO input and editing.