You asked for issues so I will raise 2.
1. Disclosure and avoiding certain deals. You have to be very careful. The average person has the right to believe that you would be focused on their best interest. Until you know if you are going to sell the property as their agent vs. buy direct and then resell you are in limbo. In some ways they should not tell you things if you are the buyer. If you are their agent you are a trusted party who can know all of their info.
So, the initial conversation can be a problem.
In many states you can not run any RE advertising without a clear indication that you are an agent. No more bandit signs and other things without the word AGENT on the sign. The state might require more than just a single word. Hence you could end up with fewer or different calls. You are clearly indicating that you are not a cash buyer, etc. You are an agent. Even if you say you are a cash buyer you look like an agent. If you call anyone, meet anyone you have to disclose very early that you are an agent so that they know what they should or should not be saying. Almost the first sentence when you call on ads, etc.
In some offices the agents can not do particular types of deals. The broker does not want the added liability. Subject-to, assignments, double closes and other creative techniques mostly. Many brokers will know less about investing than you so you need to restrict your business to their understanding.
If there is a dispute and you end up in court you are held to a higher standard as you have been licensed by the state as some sort of expert. The other side can claim they did not know that you were working for yourself or otherwise not representing this. Even if they signed things the damage could have been done with the first conversation before you told them your position.
Being an agent is about service to the public while investing is more about the deal. Hence there is almost a natural conflict.
2. Wasting your time.
If you are an agent and are not managing listings for clients you are changing the amount of time and the way you invest your time re: investing. You might find that the natural synergy is actually a drain on your investing activities.
The example above of being only a referral agent sounds pretty good. You can clearly position yourself differently. You do not have to invest a bunch of time in the listings. You are offsetting your marketing costs. You still will need to avoid the edges like bandit signs. You also will have to explain why someone who claims to be an agent in every one of their market materials, B cards, phone calls, etc is really a serious investor with cash.
In summary...
It could be that the calls you are getting are free referrals to agents you know. They need to find a way to help you out in return if they want to benefit from your market. It could also be that your marketing is attracting too many false positives so fix the marketing rather than get a license.
John Corey