External investors are doing their jobs, they are just concerned about the financials of the startup. That is why it is very important to clarify in detail the roles, responsabilities, deliverables, dates, etc.. before close the deal, in order to agreed those point of possible conflict with a risk matrix

I recommend you to refresh the relation, put in the table the situations that are concerned you, regarding the investors, always understanding the essentials of their roles, i.e. investment returns. You should realize a new process of communication with your stakeholders solving their interests and yours.