Task List disables sidebar content to Anonymous users

Problem:
Task List disables sidebar content to Anonymous users when one or more items are inserted to the list.

Diagnosis:
Sidebar content is visible when viewing the page logged in.
Sidebar content is visible with Anonymous login if Task List macro is empty.
As soon as one item is inserted in the Task List, sidebar disappears.

Affects Confluence 'Dynamic Task List 2 Plugin' version 4.2.1
Wasn't happening in 'Dynamic Task List 2 Plugin' version 4.1.7

Steps to reproduce:

1. enable anonymous login to confluence
2. verify that the default theme is configured for the space
3. create a page with an empty task list macro
4. open the page in a new browser (anonymous session)
   all good:
   
   we see the empty task list and the sidebar with content
5. with the login session, add one item to the list
6. refresh the anonymous browser
   the sidebar content is missing: