Search button doesn't work in portrait mode / narrow single pane mode

[sim6]

Describe the bug

A clear and concise description of what the bug is.

To Reproduce

1. Install in Librem5 via flatpak.
2. Open and login.
3. Click top-left search button.
4. Search pane is shown but for less than a second, so is not usable.

Expected behavior
Show search pane like other pane. E.g. Library, Saved Tracks...

General information:

• Distribution: PureOS
• Installation method [e. g. built from source, installed from Flathub...]: Flathub
• Version [e.g. 0.1.0]: 0.4.0
• Device used [e. g. desktop, phone...]: Librem5

[Diegovsky]

This is going to be a bit hard to test on my end, but I'm eager to help :)

Does it also happen in other libadwaita apps?

[sim6]

What other app can I test?

[janekbt]

@Diegovsky you can easily reproduce this issue on the desktop by making the window very small so that it switches into the "mobile" mode where you can only see the navigation bar and then click on the search symbol. This issue appears on my librem 5 as well as on my debian laptop that way. A curios side effect of this is that if you press library or any other entry in the navigation bar after having pressed on the search symbol, you need the press the back button two times to get back to the navigation bar. I hope that helps :)

Edit: We could also change the title of the issue to something like "Search button doesn't work in portrait mode / narrow single pane mode" since the issue is related to the width of the window and not the phone itself.