President Donald Trump’s ban on TikTok was temporarily blocked by a federal judge, dealing a blow to the government in its showdown with the popular Chinese-owned app it says threatens national security. U.S. District Judge Carl Nichols granted a preliminary injunction against the ban on the widely used video-sharing network after an unusual Sunday morning hearing. The judge refused to grant an injunction against a November deadline for a sale. TikTok’s owner, ByteDance Ltd., had requested the hold after the president ordered TikTok out of American app stores unless the company sold a stake in its U.S. operations to a domestic buyer. The ban, scheduled to go into effect at 11:59 p.m. in New York, would have removed TikTok from the app stores run by Apple and Google’s Android, the most widely used marketplaces for downloadable apps. People who don’t yet have the app wouldn’t be able to get it, and those who already have it wouldn’t have access to updates needed to ensure i...