Is my preload adjuster seized??

I bought a used CB500F recently, it's a 2016 model registered Sept 2016 so just over 2 years old, 4.5k milesI have adjusted the front forks now problem to make them softer (the roads I commute on are AWFUL!) but trying to adjuster the rear preload (just a single shock) and the wrench won't turn the adjuster either way, and from either side of the bike. The swingarm is in the way from either side so the wrench doesn't quite sit right so just wondering if that'd cause the issue, or if the adjuster is possibly seized? I don't remember the preload on my 125 (dual shocks) being that hard at all to turn.... via /r/motorcycles https://www.reddit.com/r/motorcycles/comments/a42mx4/is_my_preload_adjuster_seized/?utm_source=ifttt