Table of Contents Macro's 'parens' separator is not working

Issue Summary

Table of Contents Macro's 'parens' separator is not working, even if Output Type is set to 'flat'.

Steps to Reproduce

1. Create some headings
2. Create Table of Contents with Output Type set to 'flat'
3. Set Separator to 'parens'

Expected Results

Table of Contents should render parentheses as per https://support.atlassian.com/confluence-cloud/docs/insert-the-table-of-contents-macro/

Actual Results

It does not render the parantheses, instead outputs 'parens' directly.

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available