It's possible that your employer or client hasn't submitted your 1099-MISC to the IRS yet. Once they file it, you'll get an email when it's ready. Then, go to the Clients menu and select the Forms tab to view your 1099-MISC.
If you've tried this, let's try some basic troubleshooting steps. Such as clearing the cache from your browser. Web browsers collect cache to save time when loading repetitive data and images. Over time these files can become outdated and corrupted, causing issues like the one with your missing clients menu.
I'm including the links for all supported browsers that contain the steps to clear the cache below.