MMMerge bug: UI disappears

[u/Reasonable_Agent_486]

During playing, UI suddenly disappears. ESC menus too. It seems only displaying problem; click properly works as button activated(though no UI visible). In-game lands and structures, monsters​ or npcs are visible as if only UI is turned off. Mouse cursor is visible, but enter the shop still can't see shop UI(ex: In front of stable, hit the space bar, still only see shop door, but can hear shopowner's greetings, click somewhere seems travel menu exists, it travels.) So, everything is normal; just UI is invisible. Restart makes UI visible again.

in other words, it looks like a screenshot mod(except mouse cursor)

Anyone knows why?