Notes: I am using the "default light" style.
System: Firefox 45.0 on Windows 7
Steps to reproduce:
- Scroll a bit in the bar and get it to show the orange changed URL parts.
- Click right on the URL bar (on the orange parts) to show the special context menu of this addon
- Now (left)click in the URL bar at the right, so that the URL text is marked.
- Unfocus this by clicking somewhere else on the page.

To "fix" it (without restarting Firefox):
- Go to the settings, deactivate and activate the breadcrumbs again.
What happens:

(this is persistent in all open tabs)
If you click inside the bar it shows you the usual normal URL in text form, but if you unfocus it again it just shows the white space again.
What should happen:
Just display the bar as usual.
Notes: I am using the "default light" style.
System: Firefox 45.0 on Windows 7
Steps to reproduce:
To "fix" it (without restarting Firefox):
What happens:

(this is persistent in all open tabs)
If you click inside the bar it shows you the usual normal URL in text form, but if you unfocus it again it just shows the white space again.
What should happen:
Just display the bar as usual.