The following issues have been addressed in this hotfix update:
Improved audio buffer for online play
Restore missing audio in 32X MKII
General improvements to MK4
Fixed issue that caused UMK3 to reboot after Scorpion fatality
General stability improvements for Genesis titles
Pause button hold time reduced by 50%
One-Button Fatalities added for all arcade titles
General stability updates to Music Player
Additional fixes will be addressed in the coming days in another update.