It may happen that if you work with pCon.planner ME and you have installed pCon.planner Pro at a later time, when opening a .dwg file, it opens in pCon.planner ME instead of pCon.planner Pro.
To change this, go to (Windows) Start menu, Settings, Apps, Default Apps. Here you will find an overview of the different file types and the programs that automatically open them. Select .dwg and click on pCon.planner Pro.
If pCon.planner is not listed as an option, first open the .dwg file with pCon.planner Pro (Open with). pCon.planner Pro will also be available under Choose an App.