I am trying to create a new payment plugin and I am not able to get my plugin actions show inside Payment section when user has to do add action to create a workflow on click.
I guess you added element actions?
I think you can get your plugin action under element action by defining fields in your plugin, like below.
Create an element action that can trigger in workflow.
Type your code to do what you need
In the workflow page, select element action and choose the one you have defined in plugin.
Hope this help you.
Samson @ Plugin Developer