Describe the bug
After adding a Group Block, and then inserting a Paragraph Block within that Group, it's then impossible to re-select the Group block again. This makes it impossible to change settings like the Width of the Group Block or the Background colour.

Video: https://share.getcloudapp.com/E0uqqq76

To reproduce
Steps to reproduce the behaviour:

1. Insert Group Block
2. Insert Paragraph Block inside Group Block
3. Add text to Paragraph Block
4. Try to re-select the Group block to modify its settings

Expected behaviour
It shouldn't be this difficult to select Blocks

Desktop (please complete the following information):

• OS: macOS Mojave 10.14.6
• Browser: Firefox 73.0.1
• Version: WP 5.4-beta3-47379
• Theme: TwentyNineteen