The official Mega Man account on Twitter has revealed that most versions of Mega Man Legacy Collection have received a new patch:
An update is out now for MMLC on PS4/XB1/PC. The update fixes a PS4 audio bug and adds new content: Rockman (Japan) versions of 1-6!
The update notes and on the Steam page for the title add that sound effects have been added/improved on the menus, as well as Japanese language support. Steam also specifies region detection, while the PlayStation 4 cites "Various bug fixes and performance improvements."
Ah, but what about the Nintendo 3DS version, which has its own unique problem? Destructoid reports that according to Frank Cifaldi of Digital Eclipse on Twitter, who had noted that the above patch was one he had previously spoken of but could not elaborate on, states that they have still not been asked to make one for the portable version of the game.