I've already added the new task in the Salesforce1 and Lightning Experience actions but when viewing it in the detail page, there's no new task. May I know why is that?
This is the screenshot of the actions in my Salesforce1 and Lightning Experience.
And this is the screenshot of the detail page
Thanks in advance.
Adding another answer that may help people that stumble across this in the same situation I did - I just spent a fair amount of time spinning my wheels searching for a solution, and didn't think to include "Case" in my search.
If the highlight panel you're attempting to add actions to is for Case, note that Quick Actions added to the Case highlight panel actually appear on the Feed tab on the layout.
Actions on cases and work orders appear in a different way than on other records. On case and work order records, the page-level action menu contains custom buttons and supported standard buttons. Quick actions appear on the Feed tab.
Source: https://help.salesforce.com/articleView?id=actions_in_lex.htm&type=5
I noticed that, if we have record types on task object, the standard buttons will not show up in the Activity publisher. We may have to create Quick Actions to create Tasks. If we create quick actions, then they will show up in the Activity tab automatically.
Best Answer
When viewing the Activity composer related list, you may notice that some activity actions within the lightning experience do not appear on records even though those actions have been added to the Salesforce1 and Lightning Experience Actions section.
Example:
-New Event
-New Task
-Log a Call
If any of the actions above are missing and you have checked the page layouts to ensure they have been added, then it may be related to not associating a record types with any of those 3 specific global actions.
To confirm this,
Resolution
To resolve the issue, you will have up update the Record Type to be set to a default value that is one of the custom record types. --Master-- will not work.
Note: If you have no custom record types for these objects (Tasks, Events) then you won't be able to select any Record Type. If you do have custom record types, it needs to be associated with the global action to work in the lightning experience under the Activity composer.