Actually, two conditions must be met:
1. You need to type the code not in the main screen, but on the title screen.
2. Therefore, there is a limited time for typing the code and you need to type it quickly.
- For Puyo Puyo Tetris (All...
A recompile fixes it. Here (official.7z) is a compile of PR 273, which fixed compiling.
And for those who prefer it, my personal fork has an option to stretch the screen to the ~4:3 ratio the SNES displays at. Default enabled at 4:3 using...