Well, I’ll be the first to say it–this is super dumb, but here you go…
From what I discovered, you cannot just add the items in Context Menu Maintenance; they don’t show up.
To add a context menu item, go into App Studio and edit the DataView that the field belongs to.
Find the column and click this arrow item:
Then, enter some information.
Menu Text: This is what shows up in the Menu
ID: This is a unique ID name
Event ID: This is the name of the event you will need to create to launch the form.
Create the event to launch the form. More info can be found here.
And voila! I’m not entirely sure why it defaults the icon to a telephone, but you can edit the icon field to change that. Choose whatever you like: Material Design Icons (pictogrammers.github.io)
Here’s the name of the icon they use: mdi-open-in-new