Purdue is one of six universities in the House committee's inquiry.

The president-elect said he will issue an executive order Monday to delay the ban while he brokers a sale. The app has returned on web and mobile, but is not available in Apple and Google's stores.

The app had more than 170 million monthly users in the U.S. The black-out is the result of a law forcing the service offline unless it sheds its ties to ByteDance, its China-based parent company.