[ImmediateMode] Doesn't appear to work at all in URP following documentation

Hello!

Trying out shapes for the first time (and URP!), and immediate mode doesn't appear to be working, fresh project, and using the script as-is  from https://acegikmo.com/shapes/docs/#immediate-mode

Steps below, and thanks in advance! Hopefully I'm missing something really trivial.

So... sequence of events:

1.) New URP project in unity

2.) Import Shapes package

3.) Shapes after quitting and reopening the project prompts to recompile shaders to URP (cool)

4.) Shapes prompts to open shapes settings to ensure immediate mode drawing works with URP 

- though I can't see a setting to change from this prompt, no setting in the settings panel seems related to this dialogue box, am I missing a configuration stage at this point?

5.) Add a script with the code from the documentation, attach to new GO in new Scene, no lines/drawing in either Play mode or Edit mode :(