The most recent update of Premiere has a new feature where when you pull the sliders (i.e. scale from 50 to 100) it isn't immediately responsive, you have to move it significantly before it responds and then it seems to respond with the total amount you've dragged it. It's inconvenient and has me constantly fighting against the slider numbers. Horribly inconvenient and irritating to say the very least....
If that doesn't work, try resetting the Workspaces: Reset a workspace Reset the current workspace to return to its original, saved layout of panels. 1. Do one of the following: • Click the Workspace menu icon and select Reset to Saved Layout. • Choose Window > Workspace > Reset to Saved Layout. from here: https://helpx.adobe.com/premiere-pro/using/workspaces.html
If that doesn't work, try Preferences > Audio Hardware and set Input to None.
If that doesn’t work, try updating or rolling back your graphics driver directly from the video card manufacturer’s site. If NVIDIA, do a clean install of the latest Studio Driver (NOT the Game Driver).
If that doesn't work, try creating a new project and import the old one into it.