tabfern window blank (and small) on restart of navigator

[andr222]

Whenever I restart Vivaldi (generally from automatic suspension), the tabfern window (which normally has the list of tabs by window) is blank and small, in the upper left corner.

I have to kill the window (the only line without a tab description), and press the tabfern icon for the usual tabfern window to appear, with the list of all the windows and their tabs. (Everything seems to be there.)
Relatively easy to work around.

This is not new, probably like that for several years.