You know the old dating line, "It's not you, it's me". In part, this is what's likely going on with your boss. I coach with the use of the DISC assessment system. I find it a useful tool to help in communication. DISC essentially boils down to "When pushed, what's a person's fall back communication style".
Based on your limited example I'd guess your boss is a High C, with a strong High D influence.
- A High C can be humorously described as a person who says, "Ready, aim, aim, aim, aim... more data, adjust aim, aim, aim, aim."
- A High D is humorously described as a person who says, "Fire!". If you miss you can try aiming.
In other words, your boss is a data person and needs time to process. As a boss, they will have a natural High D tendency as well (Bottom Line Up Front, just the facts, interrupts). When combined this will result in the High D rising up and cutting short the conversation. Meanwhile the High C part is processing.
Your boss almost certainly knows the ideas are coming from you. They just don't have enough psychological safety to admit this after the fact. If you have an overall good relationship with them and don't need external credit, this is not a huge issue.
What you can try and do is not push for decisions to quick. Try and have two meetings for these things. One meeting is where you just discuss ideas, try not to weigh in with your own opinion at first. Give your boss time to absorb. Then in the second meeting you can push your agenda. The first meeting can even be just providing your boss with offline data.