I noticed the same problem after upgrading to Win 10 from Win 8.1. I contacted Xbox Chat Support, and then sent them an email with a screen save showing the problem, as they didn't understand what I was talking about.
No comments at all from Microsoft about this problem with treasure hunt. I was on level 112 when I updated to Windows 10. Part way in, everything is invisible. Complain on facebook, but no response. Happens not only on treasure hunt but on Microsoft Minesweeper's
I can't see the exit either, but I found a way to safely search for it.
1. Make sure you have a map left when you want to exit.
2. Position your miner on a safe spot in the last column, and eventually (if needed) on a safe spot in the next one or even two columns, and get the map of that area.
3. Once you have remembered the spaces which are free of micro light spots, remove the map by clicking OUTSIDE
of it anywhere in the visible grid.
4. Then click on those free spots and you should eventually find the exit.
You may have to repeat looking for free spots if you eliminate dirt spots while searching.
N.B. You may occasionally have to blast off some of the last column to either have access to the first blind column or have a path to potentially blank spots. Sometimes the only blank spots may be in the third or fourth blind column and you may have to
risk clicking on those if you have at least two hearts left.