What exceptions are there for wearing state awards on active duty?

No, personnel on Active Duty may NOT wear state awards.

DA PAM 670-1, 22-5
j. State awards for Army National Guard Soldiers. Under the provisions of Title 32, United States Code (32 USC), Army National Guard (ARNG) personnel are authorized to wear State awards under applicable State laws or regulations when assigned to the ARNG under the command and control of the governor or Adjutant General. The term “State” includes the 50 states, U.S. territories (which include Guam and the U.S. Virgin Islands), Puerto Rico, and the District of Columbia. The following personnel statuses are included in this authorization: Active Guard Reserve; active duty for training; active duty for special work; full-time National Guard duty for special work or training; annual training; and inactive duty training (drill status), including periods when personnel may be attached to the Regular Army or reserve of any Service, whether paid or unpaid. Personnel will wear such awards in the State order of precedence after Federal and foreign awards. UNDER THE PROVISIONS OF 10 USC, SOLDIERS ON ACTIVE FEDERAL SERVICE ARE AUTHORIZED TO ACCEPT, BUT NOT WEAR STATE OR TERRITORY AWARDS.

AR 600-8 is just the regulation on military awards does not explain the wearing of the awards on the uniform. Clear guidance is explained in DA PAM 670-1 page to 262 and I quote " Under the provisions of 10 USC, Soldiers on active Federal service are authorized to accept, but not wear State or territory awards."

No. I spent 19 of my 24 years in the National Guard of various states and while I agree with that DA PAM 670-1 states, I disagree with not being able to wear a state ribbon for emergency service in Hurricanes Katrina, Gustav (Louisiana) and Ike (Texas). I'm retired and my shit-a-giver gave out now. They look good in my shadow box!