[brazen1]

I notice using 3.7.39, I am now able to add 'Unwatched Movies' to my main menu/submenu. Unwatched movies do appear but only the first 25. Can this be changed to show all unwatched movies?

Hmmm, well that "unwatched movies" node is actually meant to use as widget and widgets are by default limited to a specific amount of items.
There are however ways to work around that:

1) Globally set the number of items for widget to a higher number (can impact performance):
Skin Settings - Supported Addons - Skin Helper Widgets ---> Configure the item limit.

2) Manually change the path for the unwatched node to grab more items. Only possible for menu items, not for widgets.
Skin settings --> Configure menu shortcuts --> Select the Unwatched Movies shortcut --> Press Change Action
--> Select custom to manually edit the adress.
Add this at the end of the address: &limit=999

Worked perfect. Thank you.