Window layering screwed

[Hugh Senior]

After years of working as expected, now any stack opened as modal is
mis-layered behind the calling window. As the blocking modal window is
hidden and not accessible to dismiss, the only way to regain control seems
to be cmd.M to show the message box (dunno why).

Anyone else got this problem? Is it the result of a recent Windows update
that has somehow screwed up window layering?

LC 9.6.12
Win11

Hugh Senior