Okay, based on your save it looks like you lost to the Minotaur and completed the entire defeat route for that, which should have sent you out of the dungeon. Did you maybe finish that and then quit playing for a while, then returned to the fourth dungeon without realizing you'd finished it? Or maybe the event bugged out and didn't send you out of the dungeon after the final defeat scene. Either way, on top of that, the event to exit the dungeon was supposed to be set up to let you leave if you showed up there after the defeat route, but it wasn't set up properly. I'll fix that, but for now you should just use the "Debugger" key item in the menu, select "Teleport to Elmgar" and then go to the guild and talk to the purple-haired receptionist to start the fifth dungeon quest. Thanks for the bug report.
Well, i have a problem that purple-haired receptionist is missing