It has everything to do with 24-bit BMP! Look at the file size of the original 32-bit BMP, 1621KB. The 24-bit BMP should be 1216KB, but your edited bitmap is still 1621KB and the file property still says it is 32-bit depth. I tried to do an export frame of your menu and resave it in Paint as 24-bit. Somehow Paint still save it as 32-bit, that’s not right, so I resave it in Photoshop and the bit depth is correct.
Anyways, VobBlanker exports the bitmap as 24-bit BMP and accepts the edited bitmap for replacement. VobBlanker will automatically convert BMP to VOB with MuxMan for you.