%P is not working

Hi,

I would like to display some indicator in the status line when in copy mode.
The man page reads
P      sets %? to true if the current region is in copy/paste mode
so I tried setting
hardstatus alwayslastline "%?%P [Copy mode] %: [Normal mode]%?"
but this did not as expected. Hitting C-a C-[ and entering copy mode,
the status line
remains [Normal mode]. How can I achieve my goal?

Thanks,

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Shotaro Aoyama