Did you try it with the USB cable hooked up between scanner and the VCI.  There could be interference with the Bluetooth connection. 

 I know that power balance feature for Ford usually works pretty well on my DS708 with the old version of the reverse engineered OE software . I'm pretty sure I read on forum that the Ford power balance function once worked well on the Maxi Sys with earlier versions of software without having to resort to Imbecilical Cording  a USB cord between the VCI and Tablet.I also thought I read there was going to be a Ford software update back last September that was to eliminate the need to have to resort to the USB cable and I even thought support mentioned that relative fuel injector flow test  would even be added.
 

We will improve this function in our new release. Please wait and it will be released next month.

                    You can add 2002 Explorer (USA) with 4.0Liter Vin# 1FMZU72E52ZB49088 to the non-functioning power balance test list. Not capable to create data-log since maxisys just stopped working went into a dark transparent Gui  with red border and clicking  (OK) didn't recover app. MS905 with Ford version 6.01. Previous version just didn't work now this version causes lock-up of app. Don't think your entering correctly as even on your screen after instructions says click (OK) but only option yes/no active??

It will be included in the new release V6.10 after half month.

                       Hmm I didn't know there was forty days in a month.