Had a dungeon level made and play tested. All was well. Made a map for 2nd level, added an exit from 1st level to that 2nd level with an entry there. And an ext from the 2nd back to the 1st with an entry there. Loaded it up to play test the transition, and I get black and grey polys and dead party members. I cant side scroll the map. I cant move the map with the ASWD or arrow keys. The easiest way for you to see what I am getting, would be to look at the STEAM forum under the thread I started yesterday DUNGEON MAKER. I tried deleting that dungeon and rebuilding a new one. I verified STEAM files. I uninstalled and reinstalled Solasta. Nothing changed.
My json file is 130k in size. If someone there at T.A. wants me to email it to them, let me know and I will. Maybe you can look inside it to see what the hell is happening with it. Same result btw with my own characters, or with your play test. The map loads fine to edit, but you can not play it.