[SalesForce] How to get custom Visualforce button to display on lightning record page

I know lightning doesn't support javascript buttons. I know there alternatives to do this with actions and lightning components. I'm asking how to do something that according to my research is supported but doesn't seem to work.

From the help article on actions in lightning, emphasis added

The page-level action menu in the record’s highlights panel (1)
contains:

  • Productivity actions
  • Global and object-specific quick actions, except for those related to creating tasks, creating events, and logging calls
  • Standard buttons
  • Custom object-specific Lightning component quick actions
  • Custom flow actions (beta)
  • Custom Visualforce quick actions
  • Custom Visualforce buttons
  • Canvas actions

Or from the Use Visualforce in Lightning Experience trailhead, emphasis added

You can create new actions for your objects, in the form of buttons
and links, by defining them on an object. JavaScript buttons and links
aren’t supported in Lightning Experience, but Visualforce (and URL)
items are
. The process of defining Visualforce buttons and links is
identical to that in Salesforce Classic, so we won’t bother to show it
here.

Easy right? So I've got a basic visualforce page using the target objects standard controller

<apex:page standardController="Opportunity">
    Hi!
</apex:page>

I've marked it as available in lightning
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Created my custom button with visualforce content source
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I've added it to my page layout (and made sure it's the correct assigned one in lightning page editor)
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But when I view an opportunity in lightning, I can't see the button
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What am I doing wrong? I'm following all the instructions with the simplest possible example I can come up with. What am I missing? Are there other factors to consider? Are those documented anywhere?

Best Answer

Same as answered in your earlier question. You need to add the button to the Salesforce1 and Lightning Actions section for the button to show in Lightning Experience. Currently it will just show in Classic version only.

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