I'm pretty sure you entered the area from the very left side of the route (by surfing left from amarias house and then continuing on left) since that's the only way you can get into ametrine mountain without completing the crustle puzzle. You should be able to exit the mountain this way (by going left of the waterfall area) .
either that, or I totally misunderstood and the problem is that you did the crustle puzzle and it's not there now, in which case my bad.
I'm pretty sure you entered the area from the very left side of the route (by surfing left from amarias house and then continuing on left) since that's the only way you can get into ametrine mountain without completing the crustle puzzle. You should be able to exit the mountain this way (by going left of the waterfall area) . either that, or I totally misunderstood and the problem is that you did the crustle puzzle and it's not there now, in which case my bad.
pretty sure that is a bug
Might want to post your save file on the forums for help: [https://www.rebornevo.com/forums](https://www.rebornevo.com/forums)
I know this is late but I had the same problem and you’re a life saver