Tasks and Log a Call Activities Do Not Appear on Salesforce Case Feed

This issue occurs when the Enable Case Feed Actions and Feed Items setting is not turned on. To resolve this, enable the setting and reapply the Chatter Feed component to the Case page layout.

Turn on the setting Enable Case Feed Actions and Feed Items:

1. From Setup, enter Support Settings in the Quick Find box, then select Support Settings.
2. Click Edit.
3. Select Enable Case Feed Actions and Feed Items.
4. Click Save.

Enabling only the said feature will not work at times. If that happens, try to readd the Chatter component on the Case layout then enable the feature once again. It should resolve the issue.