I tried out the Sounds app on the SensePlayer just now. Apart from making me login again it worked OK. I was able to transfer between tabs and play a Music mix.
I would suggest deleting the version you have and re-downloading ?from the app catalogue to see if you get? any better result.
There may be apk packages out there in the wild? which also work.
If you do get into using the app then the navigation keys like 1 to jump to the top and 7 to jump down a page are essential, otherwise? you spend unfeasible parts? of your life navigating through different elements to find the pause button for example.
I think it is 7 to jump to the bottom to the media controls, if not try? using 9 and 3.
I don't use this myself but tried it out today via the list of Apps on the Sense Player and it displayed a message saying this version is no longer supported and needs an update?
Guess it's the downside of this kind of functionality?