Accepting entity.data in a Entity Gate via other local saved values

Greetings,

I am trying to allow an entity to pass through a Entity Gate when an external value is reached (check pic, value 26). This external value is being read via a DataStore Write/Read. I can then change an entity attribute and pass it through the "Selection Gate" option.

1. I have tried to call a simulink function when the entity arrives at the server (before the gate) and perform a while loop, to check whether the external value has been reached. If it has been reached, I would update the Entity attribute. This solution stops MATLAB from functioning because of the while loop.
2. I have tried through a Stateflow but it does not recognize the output as an entity (Error:"Derived output was of type struct. 'Inherited type' is unsupported for this type and a defined bus object must be used instead.")

Is there any way to regularly check the data store value, so I am able to update the entity attribute? Please find below the screenshot.

Thanks in advance.