Within the layout tab, I am not able to zoom into an activated map frame in ArcGIS Pro 2.3.3. I need to delete the map frame and re-add it for the zoom functionality to be restored. I am using "Map Series Pages" as well. Also, the "Layout Properties" under "Map Series" don't give me the option to maintain the current map extent. If I select the option for "Center and Maintain Scale" the map extent changes slightly and I am not able to use the "Undo" tool to revert back to my previous map extent.
If it helps, Data Driven Pages in ArcMap allowed me to set a specific map extent.