Admins cannot Edit our Smartsheet after sharing permissions changed

We are on a Pro Plan account with one license. We would like two people to have the ability to edit and add data to a Smart Sheet. We have granted them editing permissions and then tried giving them Admin permissions. They are both unable to edit or input any data in the smart sheet.

The two people we wish to give System Admin permissions to have been added under User Management in the Smartsheet Admin Center and have been added as System Admins under the green share tab on the sheet itself.

When our Admins go to the sheet they can view it and see a blue band at the top saying they have limited access.

We have reached out to Support via email to resolve this issue but were told to ask the community to resolve it. Can anyone assist with how to go about giving these users permission to enter data? I have been unable to find a solution in the help section. Is it a matter of having to upgrade our plan from the Pro option or adding another license? Or is it something we are missing to activate?

Thank you kindly