I saw a thread of a guy asking about aftermarket axles on his 23 R. I tried to reply to the post but it got deleted I guess. But if you read this I had a similar issue with my 23R4 and the axle breaking.
I ended up breaking an axle a month ago or so on my 23R4. Slow speed crawling and it snapped from inside of the rear assembly. The dealer had to take the other side axle off to remove the broken side by pushing it out from inside the rear assembly. Dealer said they had never seen that before and have never had issues with Honda axles in the past. They all thought it could have been a manufacturing defect. They sent the picture to Honda and they covered it under warranty. Might help asking your dealer to submit a claim.