I use my hub without problem on windows 8.1 in the HI8 tablet. It recognices two or three devices simultanesly.
But on Android, the table only can recognice one device at the same time. A notification sais: “Warning: one more msc devices attached”
and something more telling that only a USB mass storage device can be used at the same time. Even in my old Galaxy S3 can use some USB mass storage at the same time.
Well… just deal with it! Samsung implemented many things different from standard Android, some for the better (like this), most… not so well. On Samsung devices you can connect NTFS and VFAT formatted sticks for example, which regular Android can’t read because it requires a paid licence. Never tried connecting more than one storage device myself, but seems plausible it is what it tells you it is.