It's a shame you lost it but it's water under the bridge now.
There are two things you could do in the future to avoid this:
1. NOTE: I just realized you are an agent but I'm leaving this paragraph in for the benefit of others. Use an agent. I'm just guessing based on what you shared but it doesn't sound like you used a licensed agent to present your offer. A buyer's agent doesn't cost you anything, it adds a layer of protection, and they can act as your advocate. In this case, they would probably be able to find out if the Seller's Agent was incompetent or verify that your offer was presented properly. And a good agent would likely give you the next two suggestions.
2. Prove yourself. The original offer should have included proof of funds. The Seller's Agent didn't think you were a serious buyer so my guess is they didn't even know whether you actually had the funds. You could have also included short cover letter describing your purchase power, your other investments, etc.
3. Add a contingency stating you want to present the offer in person. This works well when you suspect the agent is not presenting your offer properly. You don't have to do this face-to-face but can at lease work out the opportunity to speak by phone and ensure the Seller clearly understands your offer. After the offer is made, then the Seller can talk with their agent privately. If the agent refuses to allow this, call their Broker. In my state, agents are required to submit the offer as written and can't deny you the audience.