Aseprite v1.2.1 released with some bug fixes for v1.2:

• Don’t save transparent information on full-opaque .png files
• Fixed crash using a frame tag at the end of the sprite with a long name
• Now you can Add/Subtract selection inside the selection
• macOS: Don’t call global commands with F or T keys in Layer Properties dialog
• macOS: Fixed crash undoing/redoing when drawing
• Windows x64: Fixed GIF files encoding

More info in the blog