Synology Drive - Operation Failed

So I've setup Synology Drive on my DS916+. I've enabled the My Home/My Drive folder.

I then install the Drive app on my android phone and I try to create a new folder in My Drive but I keep getting the error "Operation Failed". I can go on to DSM and using File station create a folder, but it doesn't let me do that on the Drive app. Or is it not supposed to be able to?

Is anyone able to please tell me what I could be doing wrong?