rctmike

That makes sense, my save or scenario must be from an old version of Openrct2. So no bug, just a slight user fixable save incompatibility!

I had this happen to me too, I know I didn't intentionally set it to -1. It was displaying 254x254 in the sandbox editor, down once and back up and it's back at 254 and I can modify landscape again! I updated from a much older version of openRCT around the same time as I imported a bunch of tracks and scenarios. I figured it was a bug from a heavily cheated park in a new version with new cheats and options, but now I wonder if an older version had 255x255 options in the scenario editor and the new version does not? I don't recall the exact version I was on, but my last saves were from October 2016 if that helps. You can't place some scenery with this bug active, either. It took me a good minute to isolate that issue to my save, not my imported tracks!!!