Yes, it does sound similar. I am not a dev and phone is not rooted, but I am happy to root and/or walk through whatever steps you need to assist with debugging.
Update: I contacted Sony. After some back-and-forth they sent the below instructions. After I updated software I tested the device once. Three ANT+ sensors were detected/tracked and seemed to report accurately for over 1.5 hours. I am traveling now unfortunately so cannot test again for a few weeks, but something positive seems to have changed in the Sony code update.
Thanks.
Ben
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Dear Benjamin,
Thank you for contacting Sony Xperia™ Online Support.
In regard to your inquiry, we are sorry to hear that you are having issues with your device's ANT+ connectivity, however we'll be more than glad to assist you solve the issue as soon as possible.
In this case, the issue could be due to a minor bug in the device's software, therefore we suggest you perform a software repair in order to rule out any possible bug the device could have. Please keep in mind that this process erases the internal memory of the device, so we recommend that you perform a Data Back Up before proceeding with the software repair guide below.
We have an extended guide that should help you fix the issue on your phone, please follow the instructions carefully:
Visit this link:
http://www.sonymobile.com/us/tools/pc-companion/
Click on Download PC Companion
Run the software and install it
Turn the phone off and disconnect it from the computer
1. No matter what the program says do not connect the phone until you complete step 9
2. In the welcome screen you will see the different modules available for you including the "Support Zone" option. Click on "Start" below it.
3. On the next page Click on "Start" under "Phone Software Update"
At this point if you get an error stating that "Unable to install update components" or "Server is busy" , then please proceed to step 12
4. The program will say that there is no phone connected. Click on the option below that reads: "Repair my phone" the program will issue you a warning about the content that you will lose during the update
5. Choose the option to continue.
6. The program will issue a final message warning you of possible data lost during the update. Click on the checkmark and then on "Next".
7. After that, the program will download the necessary information (5 to 6 minutes) and it will present you with a list of phones.
8. Choose your phones model from the list then click on "Next" then you will see a new section telling you how to connect the phone. (don't connect it yet)
At this point the phone must be off and disconnected from the PC.
9. Connect the cable to the PC not to the phone, then while pressing and holding the indicated button (in the steps on screen an specific button will be shown for you to press on the phone) connect the cable to the phone and keep holding the indicated button until the program says "the update of your phone has started..." (in some cases a message of "Installing drivers" will appear before the message of "the update of your phone has started..." is shown.)
10. If you failed to follow the steps correctly the phone will turn on and it will request that you "Proceed with the following steps, slide down the notification bar", If this happens disconnect the phone from the cable, turn it off and repeat from step 9).
11. If the phone is connected properly, PC Companion will proceed with the update ( It will tell you to let go of the back key) then wait for the update to finish and follow instructions on screen to disconnect the unit.
Dear Customer,
12. If "Unable to install update components"
1. Close PC Companion
2. Install Java from:
http://www.java.com
3. Start PC Companion again and try to do the software unlock process once more.
Note: If you wish only to update the unit wait for the program to open and then select the quick link on the upper left corner that says "Update Phone/Tablet" and follow the instructions to perform the update. (the PC may request for the phone to be placed in Mass Storage mode. Do this by going into Settings>Xperia>Connectivity>USB connection mode)
As part of Sony Mobile's commitment to excellent customer service, we offer a wide variety of mobile products to suit your lifestyle. If you require more information, or have any other questions, please visit
http://www.sonymobile.com or call us at 1-866-766-9374.
Kind Regards,
Leonard
Sony Xperia US Customer Services