With Epiphany 44.3 and WebKitGTK 2.40.3 on a Wayland GNOME session, clicking the "Import" button in the network inspector does not do anything at all. It does not even open a GtkFileChooser to pick a .HAR file (but when it eventually does, it should filter for the compatible mimetypes if it doesn't already, while we're at it).
*** This bug has been marked as a duplicate of bug 245216 ***