PS4100 in Pool - Convert from RAID10 to RAID6 - No free spac

Hi, we have an old PS4100 (well two actually), configured in a Group. We needed to gain space to allow us to carry out a re-jig of the fabric. The conversion from RAID10 to RAID6 is 33% through, and at the start we also ticked the box to 'Immediately expand group capacity'. The issue we have is that the extra capacity isnt showing yet? Is that normal despite ticking that particular box?

Thanks for any help.