GLEN BURNIE, Md.—When Chesapeake Bay Candle decided to build a U.S. factory, founders Mei Xu and David Wang thought it would take nine months and cost $2.5 million.

But $3.5 million and 13 months later, the couple is still waiting for their final occupancy permit. A temporary sign is draped across the front of the beige concrete structure, a former liquor warehouse on the outskirts of Baltimore.

"I...