Issue fixed with this function
Lua Code:
function ab:FixMBBR()
for i = 1, 6 do
local Button = _G['MultiBarBottomRightButton'..i]
Button:SetAttribute('showgrid', 1)
Button.noGrid = nil
Button:ShowGrid(ACTION_BUTTON_SHOW_GRID_REASON_CVAR)
Button:Show()
end
end
SetAttribute has caused an issue with MultiActionBars.lua from Blizzard. All buttons are set to nil, only buttons 1-6 of the MultiBarBottomRight are set to true. nil or false shows the grid and the button while true hides the button.
In the end, @humfras got me on it. Thanks for that