I was refering to the after activation. Yes the Data page is activated with a Switch, but once activated its treated as a 4th page. but pressing Right on the Forms page, the 3rd page, does nothing. That's because both plugins handle max dex's pages differently and yours takes priority.
I found a way to solve it. In 011_RegionMap_Pokedex_v211:
elsif Input.trigger?(Input::LEFT)
oldpage = @page
@page -= 1
@page = 1 if @page < 1
@page = 3 if @page > 3
if @page != oldpage
pbPlayCursorSE
dorefresh = true
end
elsif Input.trigger?(Input::RIGHT)
oldpage = @page
@page += 1
@page = 1 if @page < 1
@page = 3 if @page > 3
if @page != oldpage
pbPlayCursorSE
Changing both "@page = 3 if @page > 3" to "@page = 4 if @page > 4" lets you acces it like normal. I belive this is because the Modular UI scenes has another handler for max pages and yours sets it to a maximum of 3 like the base Essentials. I don't know if anyone else is having issues with it (I din't before the update of those plugins so this is odd), but in case someone is this is a simple fix