I have enabled lightning profile for a customer and trying to add open activities related list on the detail page of custom object. But the open activities related list is not visible on the page.
Could you please let me know how to do it? Attached is the picture on my classic page layout
I want the same view on my lightning page.
Currently its not possible to sort open activites.Here is the idea https://success.salesforce.com/ideaview?id=08730000000BqX6AAK
Workaround : Create a list button on Task
with URL value as /007?id={!Account.Id}&rlid=RelatedActivityList
Add the button to Open Activities Related list of Account Pagelayout.Then on Click of button it will open new page where you could sort open activities on any field.
After some research I found that it is not possible. Quick actions that open lightning components can be placed on top of page only.
https://help.salesforce.com/articleView?id=actions_in_lex.htm&type=0
Best Answer
I think Allow Activities Option is not enabled on the custom object.To enable it, check below the following points.
Go to Setup.
Open Object Manager.
Click on Edit button of your custom object.
Enable Allow Activities option.