EmptyScriptAdder.lua is in my Plugins folder. Clicking the Plugins Folder icon confirms this.
Toolbar button shows up greyed out, but never becomes clickable and Manage Plugins remains always empty. The new local plugin never shows up in Manage Plugins.
I’ve copied and pasted the code from Step 4 of “Adding a Toolbar Button” and also tried copy/paste the code from “Supporting Undo/Redo” section. I right click the Script and select “Save as Local Plugin…” each time, still no success.
When you use “Save as Local Plugin…” or install a new plugin, Roblox automatically refreshes all plugins. If plugins aren’t refreshed, you have to manually restart studio to make Roblox Studio reload plugins in the Plugins Folder. I’m guessing you edited the .lua file manually to copy paste the code, so it didn’t update properly in studio.
Oh, I think I know what your issue is. You can’t use buttons in the plugin toolbar unless you’re currently looking at the viewport. You don’t have to close the script editor, you just have to click out of it to view the main viewport.
Local plugins don’t appear in Manage Plugins because that panel is specifically only for installed plugins. You have to manage local plugins through your own file system or through the plugin itself (not creating any plugin materials if conditions aren’t being met, for example).