Unable to add Wiki macro in pages with old editor

Issue Summary

If you added a Wiki macro (Markdown format) to a page using the old editor, you can no longer add Wiki macro on any other pages that uses old editor.

Environment

Pages that uses old editor (TinyMCE)

Steps to Reproduce

1. Create/Edit a page that uses old editor
2. Add a Wiki macro
3. Switch to "Markdown" format and add something like *test* which should be rendered as test in Markdown but will be shown as test (a different bug: https://jira.atlassian.com/browse/CONFCLOUD-65842)
4. Try to add another Wiki macro, no popup dialog will appear

Expected Results

• Able to add more Wiki macro

Actual Results

• Nothing happens

The below exception is thrown in the browser console:

Uncaught SyntaxError: Unexpected token M in JSON at position 0
    at Object.parse (<anonymous>)
    at Object.get (persistent-storage.js:29)
    at An (editor_plugin_src.js:97)
    at tw.<anonymous> (editor_plugin_src.js:387)
    at i.exec.<computed> (atlassian-editor.min.js:1)
    at T.execCommand (atlassian-editor.min.js:1)
    at tw.execCommand (atlassian-editor.min.js:12)
    at tw.b [as execCommand] (batch.js?externals=__local-default__&locale=en-GB:508)
    at adg3-plugin.js:160
    at HTMLLIElement.<anonymous> (adg3-plugin.js:441)

Notes

• Once the error is triggered, you can no longer add Wiki macro in any old editor pages regardless if the page in question has an existing Wiki macro

Workaround

• Use the new editor (if possible) as it supports Markdown natively
• Do not use the "Markdown" format when adding the Wiki macro.
• If you already run into this issue, you can clear your browser's local storage for the site. Then you should be able to add Wiki macro again. Just be sure to add it in the "Confluence Site" format to not trigger this bug again.

Steps to clear local storage for your Confluence site:

• Google Chrome:

1. While on a page in your Confluence site, open the Developer tools (Option+Cmd+i in Mac or Ctrl+Shift+i in Windows/Linux)
2. Switch to the Application tab
3. On the left bar, under "Local storage", expand it and you should see your Confluence site URL like https://an-example.atlassian.net
4. Right click it and choose clear
5. You should be able to add the Wiki macro again

• Mozilla Firefox:

1. While on a page in your Confluence site, open the Developer tools (Option+Cmd+i in Mac or Ctrl+Shift+i in Windows/Linux)
2. Switch to the Storage tab
3. On the left bar, under "Local Storage", expand it and you should see your Confluence site URL like https://an-example.atlassian.net
4. Right click it and choose clear
5. You should be able to add the Wiki macro again

• Apple Safari:

1. While on a page in your Confluence site, open the Developer tools (Option+Cmd+i)
2. Switch to the Console tab
3. Run localStorage.clear() in the browser console at the bottom of the page (looks like a line that only shows >)
4. You should be able to add the Wiki macro again