Today I tested my new memory card - a Scandisk Extreme Pro 32 GB class 10 95MB/s card.
I was very surprised the camera mentioned I only had 0,5 hour of recording time - also when I re formatted the card twice. I was using the AVCHD mode 50 p 28 Mbps.
Same amount recording time, also when I switched to MP4 and Mov. I double checked the card on my notebook just to be sure they didn't place a wrong sticker - but it actually is 32 GB.