Having the exact same problem, had to revert to 0.12 as well.
I went as far as starting from scratch with a new SD card and and fresh eMMC. Still same issue.
Just a note to save others from the trouble. I also tried.
1) Uninstalling the game. Reinstalling it. Adding 1.2.0 update. Applying BCAT with May Day files
2) Reset Save Data from Nintendo System Settings. Starting new game until first save is possible. Applying BCAT with May Day files.
Both...
Not exactly a noob and followed the instructions to the letter. Still stuck on ver 1.2.0. Also tried many different suggestions but nothing seems to be working.
Using that method I only managed to launch YSmenu, the other firmwares don't load. I managed to find a modified boot.eng from another multi-boot compilation that at least allowed me to boot Sakura and Wood
I own an iTouch2DS and I extracted the files into the SD card but I get the error message no boot.xxx.
Do I need to rename a file or copy a file from somewhere else?
Thanks for the help and sorry if this is a stupid question.