Not always true, as I just ran into this issue with a 2811 not seeing/formating a card that Windows could read. Changed the allocation size to 16kb and the router could see and format although windows couldn't read the CF card afterwards. Changed it...
I know this is an old post but maybe the info will still help.When you format the CF card on windows (8.1), change the allocation unit size to 64 kilobytes. I ran into the same issue using a 512mb Cisco branded card. My default allocation unit size ...