Not sure but you can try following workaround, you can save a table in the following format "<table></table>" in a description field and while displaying the list of tasks, use this to render the HTML output of description field <apex:outputText value="{!description_field}" escape="false"/>
Not sure but you can try following workaround, you can save a table in the following format "<table></table>" in a description field and while displaying the list of tasks, use this to render the HTML output of description field <apex:outputText value="{!description_field}" escape="false"/>
The behaviour you are expecting is related to the known issue below
https://success.salesforce.com/ideaView?id=08730000000cJNzAAM
Thanks
Ramesh
https://help.salesforce.com/articleView?id=fields_using_html_editor.htm&type=5
Thanks
Ramesh