Number of keys supported for custom keybindings

[tictoccloc]

Do custom keybinds only support up to 3 key combinations? I was trying to bind m4 to ctrl+ shift + alt+ f15 (0xA2 0xA0 0xA4 0x7E) which should switch gpu mode to standard, but afterwards pressing m4 does not work as intended. However, binding m4 to ctrl + alt + f15 and inputting shift + m4, or binding m4 to shift + alt + f15 and inputting ctrl + m4 works. I couldn't find any notes about this in the custom hotkeys action page.