I saw this earlier and had planned on responding.
Roger is correct, you need to have a good solid GPS in the ADS-B in
device, and a lot of the Stratux units use a simple USB plugin
device that contains the antenna internally (see image below), the
problem with this design in the Stratux is that it sits right next
to the SDR receivers (Software Defined Radio) which generate a bunch
of noise and can prevent the GPS from getting a good GPS lock. My
suggestion for a GPS receiver on the Stratux is a VK-162 GPS, with
one strong caution specifically with the external part, there is a
small but very strong magnet in bottom which can potentially
interfere with your compass, I would highly recommend you remove the
magnet by simply peeling up the sticker and removing the magnet on
the bottom of the antenna.
With the GPS module pictured I rarely had more than 5 birds in use
at a time and sometimes would lose my position, with the VK-162 the
Stratux is usually using 8 or more birds at a time and is rock solid
with its position.