Run the Auto-configuration Wizard (tools menu) and apply the settings it gives. Do not change a thing. Restart OBS (yes, restart it) and test as is for no less than 30 seconds doing all what you normally do, or plan to do. Just one time, don`t go happy starting and stopping the testing, do it just once.
Now look inside Help menu. Upload the current log file and paste the url to the log in here. Click on the Analize button to start troubleshooting common issues.