Intermittent availability of Android emulator for Test Target

[Ben Rubinstein]

I'm having trouble running tests on the Android emulator from LiveCode on Mac. 
  Sometimes I see it in the "Test Target" menu, sometimes I don't.  This is on 
various versions of LiveCode from 5.3 onwards.  I restart AVD, restart the 
emulator, restart LiveCode, reselect Android in Standalone Application 
Settings... I can't find the magic sequence that makes it come back.  But 
sometimes it has come back.

Does anyone else have this problem?  Has anyone got a routine which works?  Or 
is there something stupid which I'm doing that would account for the problems 
I'm having?

TIA,

Ben