I think it's not really a technical problem. I guess they want to sell their own cloud solution. I have used it for a while, the web interface is quite nice but for iOS devices, there is no offline mode which leaves this option unusuable. I even lost data when I stated to work on a map on an iPhone and then lost connection. With their close integration with MS Office, there is no way around Ondrive integration on iOS. As this feature is more important to me as many of the "fancy" things that were introduced with the latest version, I already started to look for alternatives. Besides the fact that MindMap is not really a cheap software.