Many companies planned to reopen offices after Labor Day. With COVID still around, they’re rethinking that.

This summer, executives at health-care-technology firm Epic Systems announced a plan: Most of the 9,500 employees at its 1,000-acre campus in Wisconsin would be expected back in the office in September. The company, like many others, says its employees do their best work when they can collaborate in the same space. But blowback to the mandate was swift. Employees expressed fears about safety and spreading the new coronavirus. Local health officials questioned the move. So Epic joined legions of other companies making late-in-the-game...