It is scaling from the center, typing .75,.75 (for example) will scale both x and y directions the same. You might need ; as a separator depending on your regional settings.
Try repairing the SketchUp installation. Find the downloaded installer in your Downloads folder or get it from Download All | SketchUp Right click on the installer and choose Run as administrator. Then choose Repair.
“Try repairing the SketchUp installation. Find the downloaded installer in your Downloads folder or get it from Download All | SketchUp Right click on the installer and choose Run as administrator. Then choose Repair.”