Suggest you add current to your Pi supply voltage. 2.5A is a little low for the B+ and unless you need the powered hub for something else, I think it can be omitted, and upsize your Pi supply to may be a 5A supply.
Ramp/Twinkle issue . . . could be your dongle, but also the Export Timing. If you are using 25ms, try 50ms. I've not found a case where 25ms is needed, so until you actually need 25ms timing, use 50ms.
Good luck, and hope the simple timing change works for you.
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