Document properties dialog doesn't open first time

Summary:

When opening Document properties dialog it doesn't appear the first time.

Steps to reproduce:

• Open Inkscape Either: - Click on: File > Document Properties Or: - Ctrl + Shift + D

What happened?

The dialog didn't appear.

What should have happened?

The dialog should have appeared.

Version Info:

- Inkscape Version: 1.0 (4035a4fb49, 2020-05-01)
- Operating System: ArchLinux
- Operating System version: Up to date

This bug wasn't present a few weeks ago.