Strange behavior with brand new Jaybird Vista headphones

My new Vista headphones show an odd behavior, which leads to a dramatical but reversible degradation of the sound quality.
Maybe some of you can test this briefly with your Vistas to see if my headphones are defective. It won't take two minutes, I promise! If you notice the same strange behavior, it's probably a bug that can hopefully be fixed soon with a firmware update.

Now for the test:
1. Remove both headphones from the case.
2. Insert the right bud and listen to music. Preferably with lots of hi-hat.
3. Put the left headphone into the case and close it. Sometimes it is also doing this, without needing to close the case.
I now hear a serious degradation of the sound within seconds.
4. open the case and remove the bud. Almost instantly the sound is perfect again.

If the left Bud is in the case, the sound gets lousy. As soon as it is out again, the sound is immediately great again.

For testing I took Toxicity from System Of A Down. Especially from 0:16 to 0:19 the difference is easy to hear.

Another thing I noticed is that some of my end devices cannot adjust the volume. Smartphone, tablet and PC work fine. Smartwatch and TV cannot change the volume. Other BT Headphones work fine with those devices. So I have to change the button assignment on the buds app.

If it wasn't for all this, these would be the perfect headphones. Super sound and very good fit during sports.

PS: Dear support, my request to you via contact form has unfortunately remained unanswered. So please don't suggest that I should write an e-mail to get in touch with you. If you can explain this, please help. I'm not sure, if this is expected behavior.