Try enabling predicted circuits in sbws
Torflow doesn't stall. I compared the Torflow and sbws tor options. sbws sets __DisablePredictedCircuits 1 and Torflow does not.
So you could try removing that option from sbws: https://github.com/torproject/sbws/blob/10cda4bfdff1b777f5005ce9f5a433290aafa216/sbws/util/stem.py#L75 https://github.com/torproject/sbws/blob/10cda4bfdff1b777f5005ce9f5a433290aafa216/sbws/util/stem.py#L199
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