The fix I devised back then (requiring the experimental "force claim interface" option) worked for most of you, but not for everyone.
After working with a few beta users, I'm now releasing two new versions of Sportablet (7.5) and Uploader for Garmin (6.6). They change the connection procedure, so the option above is no longer necessary (it kicks in automatically) and has been disabled. This change should fix the initial connection problem for the rest of you. I use "should" because my control over things is limited when I'm using the dynastream service, but results from the beta are positive.
Note: there are no other changes in this version. No changes to the code uploading to web apps, no changes to the portion of code doing the actual ANT+ data transfer - the only change is in the portion of code turning on ANT+ and beginning the discovery of ANT+ devices.
This new version offers a slightly more useful diagnostics in a few cases when the connection breaks down in a way that I can't recover. It will say "you may have to restart" (as in some cases the app still manages to recover). When you see that message, my suggestion is that you click on Cancel and then on Retry.