Does anyone else have trouble getting their Garmin 910xt to detect/pair with your own cadence sensor under race conditions? It pairs fine normally, but being on a rack with so many other Garmins screws it up. In races I don't usually swim with my Garmin because I don't want to risk the quick release getting kicked off and if it's on my wrist it will be hard to see on the bike. The plan is to have it set for a bike/run auto-multisport. So far I have had no problems getting good data for training, but it all falls apart in races. Under race conditions it detects everyone else's cadence sensor but not mine. At Rev 3 Williamsburg after a lot of fiddling while riding I got it to finally pair about 5 mi into the race after the pack had thinned out. Last weekend it never detected the cadence sensor at all, but it's working fine again now. This is really frustrating and Garmin's support forums are absolutely terrible. Let me know if anyone has a solution for the pairing issue while other sensors are around.
I think the solution is to pair the device before you rack the bike.
I have had it pair before leaving transition for the swim, then not work later and I have had it just not pair at all while I am around all the other bikes. It's driving me nuts and there's no way to test it because there are no other instances when I am around that many other Garmins.
I swim with the quick release on and have been in a fair amount of contact while swimming with no issues. No my problem is remembering to grab it post ride in T2. Twice I've raced out of transition without it. :)
Similar to what Malissa said, the 910xt should maintain the pairing that you set beforehand. It should stay paired day to day and week to week while you're training too.
Have you tried replacing the sensor's battery? My speed/cadence sensor gets flakey with my 310xt when the battery gets low.
I know this didn't directly address your question of picking up your own sensor with other sensors around, but I'm throwing it out there in case it might help.
Also may want to check the memory and clear out anything older than a month. Likely not related but helps with the functionality of my 910 XT.