Yeah, you need to research at least one proposal type
Viewing post in What are prerequisites for getting a business proposal?
Okay, that's weird. Maybe try a staffer with a higher "Deals" level? Although you should be getting proposals even with level 0.
This sounds like a bug, or maybe you have some weird edge case, so here are some other things to try: change the business proposals policy to neutral; change the vibe policy to neutral; remove pushes; change staffer's preferred proposals setting to default; hire more idols;