Interesting.... I have a soundsport with 2.7.7 but I have an iPhone 7+. So I did an experiment. I removed it from my bluetooth list ("forgot it"). So I then paired it sucessfully by holding the button down (did not use the app to pair). And then I used my MP3 player and it played fine in the soundsport. So that means one of two things for me at least either (1) your recently purchased soundsports are somehow different from mine - my 'manufacture date' is "3/19/17" OR (2) there is an incompatibility with your phone hardware or its operating system.
By the way, my soundsport currently 'suffers' from the same BLE problem as the QC 35 though not as often. It will also on occasion turn itself on.
I just wanted to jump in here and remind everyone that if you have an issue with your headphones that cant be resolved from standard troubleshooting, you can always contact your local support team for help. Here is a link you can use. Click on your country, scroll down until you see "Contact Us."
Tony G - Community Support
So, good news! I was reading in another thread that someone went in manually to the 'advanced' drop-down menu in the update page on their computer. So after disconnecting everything again (just like it would have been out of the box), I forced the 2.7.7 update onto the soundsports again. I then connected it through the bluetooth device list on my Pixel before adding it through the Bose Connect app, and it seems to be working fine now!
The thread in reference can be found here Firmware Update issues, and I'll include the steps below to help anyone else experiencing similar problems. Thanks!
0. Make sure that you have Voice Prompts turned on.
1. Go to btu.bose.com on a PC or Mac computer
2. Plug your headset into the PC or Mac via USB
3. Click on the Soundsport product
4. The update page will load and tell you the software is up to date
5. When on this screen type the following 5 keys sequentially: ‘a’ ‘d’ ‘v’ ‘<up arrow>’ ‘<down arrow>’. Click the dropdown and select the previous firmware, then click "apply changes".
6. The Firmware will begin to load. This process may take between 5 and 10 minutes depending on ISP and network conditions. Do not disconnect the headset until the process is complete.
Thanks for your post and welcome to the community. I am very sorry to hear that you are having this issue, however I would love to help.
Can you please confirm which troubleshooting methods you have attempted from this thread?