Data on how employees feel about requirements to return to the office full-time spell a warning for Elon Musk and other company leaders.

The trend also comes as employers get competitive in a hot job market.

'If you don't show up, we will assume you have resigned,' Musk told Tesla and SpaceX employees. It's a move many call risky.

Building employee connections and working to individualize wellbeing can help HR leaders boost retention.