It’s recommended to only use the PTR boost on fresh level 1 characters because using it on copied characters will remove your gear from your copied state!
Now that Season 5 PTR is live, many players have found out the hard way that using the PTR boost on copied characters results in losing all their gear. Blizzard now advises only using the boost on Level 1 characters.
Just putting a PSA out there that players should not use the boost on existing characters copied over to the PTR.
This will remove and replace their character state with the character boost and you will lose your character inventories and gear from your copied state.
We will look to improve this flow in the future.
Please only use the boost on fresh level 1 characters created on PTR.