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Yup. I pretty much get the feeling that you just can't power a USB flash drive and AND charge an iPhone from the same front port.Reading the production description for Onvian USB Splitter Cable
It seems the one with the red notch is charge only, and doesn't provide sufficient charge for iOS devices. The other cable that doesn't have any red notch will work for charging and data.
Based on this, I don't think this cable will work. What the OP (and me) need is something that will have Data on one of the cables and enough charge for iOS device on the other.