Josh Giddey might be in the clear legally, but he is still under his employer's microscope -- the NBA's review into claims he had an improper relationship with a minor remains ongoing, TMZ Sports has learned.

Sources tell us nothing has changed as far as the Association is concerned ... despite Newport Beach PD recently closing its investigation without the 21-year-old Oklahoma City Thunder guard being charged.

As we previously reported, the Giddey case ended after officials found no corroborating evidence ... as the minor and her family declined to speak with officials.

"After a thorough and exhaustive examination, we have completed our investigation into information that was circulating on social media involving Josh Giddey," Newport Beach PD said in a statement.

"Our detectives have reviewed all of the available information and were unable to corroborate any criminal activity related to Mr. Giddey."

Adam Silver said in December the league would take a "backseat" while police conducted its investigation ... so with that being over, it sounds like the NBA is grabbing the wheel once again.

Giddey has not spoken on the scandal ... and has remained active for the Thunder throughout both investigations.

In fact, he was asked about the case being closed Thursday morning ... and declined to comment once again.