I'm not sure where to post this info, so I'll start here, and move it elsewhere as needed.
I managed to compile Mission Planner from the source repository and fix the bug with APM 2.5 not connecting consistently.
For anyone interested, here is the solution...
//@line 328 of the file 'Mavlink.cs',
//within the 'OpenBG' function:
So, increasing the thread sleep timeout fixes the problem. I'm now able to connect 100% of the time via USB. I guess the next step is to alert a developer and have someone fix this in the release version? Can anyone help me out with this?
feedback is welcome...