Old bench warrant doesn't make sense

Trying to figure out how my significant other acquired an active bench warrant on Hawaii island.

Backstory: June 2018 - SO was visiting Big Island from the mainland where marijuana is legal. SO bought $20 of marijuana from a random guy, and the police apparently were watching them. They arrested them and brought them back to the station. Questioned my SO and he was released and never charged with anything. No citation. No booking.I guess they thought my SO knew this guy and was part of his drug selling but my SO obviously didn't know the guy.

Now: We now live in the state Hawaii (not Big Island though). We were doing a random eCourt Kokua search of my SO's name and we found a bench warrant for him! He had absolutely no idea. Here are the details:

• Bench warrant issued in February 2019
• Case is INACTIVE
• Bench warrant is active
• Charge is "Promoting a detrimental drug, first degree, felony class c"

How does the bench warrant not match the crime? My SO was never charged with anything and he was let go. He would not lie to me.

We do not see anything on eCourt Kokua about any crime he committed. All we have is a police report # that I have requested through the mail (haven't received it yet).

What could have possibly caused all of this?? Clerical error? Could the prosecutor accidentally filed the bench order under the wrong person? How does buying $20 worth of weed turn into a class C felony?