Only the same issues that affect all of our pumps with VDM and one that is unique to the Stream 3 with all controllers.
The Apex cable tends to fit loosely at the pump socket, this is generally remedied by either trimming the rubber boot on the cable or pulling it back allowing further insertion.
The control voltage changed in mid 2015 from 0-8V to 0-6.5V, because of this the speed settings shown on the Apex are not accurate, this won't affect operation except at low speeds, the range is much tighter so what was 30% for example is now closer to 20% and so on. This change was made because it increased the efficiency and durability of the control system.
The Stream 3 does not respond well to off and on, however it can run as slow as 5% speed. On start up the pump has to do a start up sequence to levitate the rotor, this applies to all controllers even our, for this reason off should not be used as a delay of about 3 seconds will result from the start up sequence and if rapidly pulsed on and off it will never actually run, use 5%- 100% instead.