This problem has been going on for several months. I've deleted and re-installed the Channels app several times, installed new CAT6 cables, replaced the antenna VHF single rods and more until I realized that the Nvidia Shield TV Pro was the only device having this issue.
Until about a week or so ago, it would pause and show no notification.
I haven't had a chance to test it with Tuner Sharing enable. I'll test it for 30 minutes to an hour and get back with you.