BibTech,
We appreciate the clarification. Have you checked with the manufacturer for any firmware updates? We would also suggest testing the issue in another user. Being able to see if the issue occurs in another user account will to identify if it is something that is affecting your entire system or just one particular user account. To do this, you'll want to set up a Test User account and then try to replicate the issue in that account.
1. Choose Apple menu > System Preferences, then click Users & Groups.
2. Click the lock icon, then enter an administrator name and password.
3. Click the add button (+) below the list of users.
4. Complete the fields shown for a Standard or Administrator account, then click Create Account (or OK).
5. Go back up to the Apple menu in the upper left of the computer and select "Log Out". At the login screen, choose the "Test User" just made.
6. Once inside the Test Account, try to replicate the issue to determine if it just occurs in one account or on the whole computer.
Thank you.