work me / myself out

[perpend]

The text is from Dowton Abbey. (A show set in the 1920s.)
'
One of Lady Mary's suitors says something like: I can't work you out.
Lady Mary replies: I can't work me out.

I understood the gist and had a delayed understanding of what's meant (when I watched), and then I got it.

I'm curious how current-day BrE speakers feel: I can't work me/myself out.

Is there a preference, or are both still current?

 

[DonnyB]

It works as a neat response to "I can't work you out", but it would come across as a very strange thing to say on its own. I wouldn't label it as old-fashioned (1920s vintage) if I heard anyone say it.