Google confirms "a small subset of users" have been temporarily unable to access the News tab filter in search results pages as part of ongoing testing (Sarah Scire/Nieman Lab)

Sarah Scire / Nieman Lab:

Google confirms “a small subset of users” have been temporarily unable to access the News tab filter in search results pages as part of ongoing testing  —  The News filter disappearing from Google search results for some users this week won’t help publishers sleep any easier.