I have a Logic Pro X project (10.4.5) on latest mac (10.14.5) that was saved with Scaler 1.7.0. I upgraded to 1.8.0 and the project crashes on startup. “Unable to load ScalerCntr” exactly spelled out like that. I downgrade to 1.7.0 and it starts.
I have the same setup and no issue here. Try this: Install Scaler 1.8. Open a blank (not from template) Logic File and load Scaler as a Midi FX. Quit. Now try and open your section with 1.7. If that doesn’t work open a new session of Logic and go to Logic~Preferences~Plugin Manager and search for Scaler. Select all instances and then hit Reset and Rescan Selection in the bottom left. Now open your old session. Please report back.