Increase Indent does not postback on first postback

I am using the fckeditor with FCKConfig.EnterMode set to 'div' (not sure if this is relevant). When I use the indent button and click 'save' the indentation does not get saved. However, if I indent again and click save then the indetation gets posted back correctly. This seems like a bug. Can anyone else who has seen this shed any light?

Thanks,
Mark