Adding a Macro using a Custom Editor doesn't work in a Jira Project page

Issue Summary

Adding a Macro using a Custom Editor doesn't work in a Jira Project page.

Steps to Reproduce

1. Install the test app by using the https://dx-macro-custom-editor-dialog.glitch.me/connect.json URL (the source code of the app is available here)
2. Add the macro to a Jira Project Page using the /DX Macro Dialog command
3. Click on Insert

Expected Results

The macro is added to the page.

Actual Results

The macro is not added to the page and the macro dialog doesn't close.

Workaround

Add the macro directly in Confluence. This issue only occurs when adding the Macro while editing a Jira Project Page.