Here is a checklist that you will want to run through:
1. Try plugging the USB cable into a different USB port. If you are using a USB Hub, try plugging directly into a USB port on your Mac. (If you are running a newer MacBook with a USB-C port, you will need to use a USB Hub.)
2. Try using a different USB cable.
3. Make sure that you have downloaded the latest version of Universal Control from our site. Here is a link to the downloads page.
4. Try using a different xlr cable for your Mic.
If you continue to have an issue, log a ticket from your my.presonus.com account using the "Support" button.