The problem only happens with custom style set, everything works OK without style. If I run from terminal, I get these errors when I try to select an item with keyboard arrow keys:
(wofi:13650): Gtk-CRITICAL **: 21:10:40.340: gtk_widget_grab_focus: assertion 'GTK_IS_WIDGET (widget)' failed
(wofi:13650): Gtk-CRITICAL **: 21:10:40.340: gtk_flow_box_select_child: assertion 'GTK_IS_FLOW_BOX_CHILD (child)' failed
Can you please attach the CSS you're using as well as your config(if you have one) and the command line options you're using. I and others I know use custom CSS as that's one of the main features and no one I know has seen this so I need more to go on.
By experimenting with commenting out various parts of CSS I found that the critical part is this:
#inner-box { margin: 5px; }
Without it everything works, with it - the issue happens. Renaming the config file changes nothing/
#inner-box { margin: 5px; }
c65afb6a4394 should fix it