v1.4.9 is out as of a few days ago. From the notes in my initial Strix Music write-up:
For Windows 10 Mobile phones, you need the main 'app package' (a file ending in '.appxbundle'), the Visual C++ runtime package (a file ending in '.appx' and with 'ARM' in its name), and the certificate file (ending in '.cer').
The easiest way to install these is just to put them on your phone using a cable from your Windows PC or (as below) by adding them to your phone's microSD. Note that you can't download the files directly in (Windows 10 Mobile) Edge as Strix Music's site isn't Edge-friendly.
Of course, if you've installed the previous version then the 'runtime' and 'certificate' will already be in place, so all you need to grab and install is the 'app package'. And note again that the download has to be done on the desktop for now. Hopefully in the future options like Zella Store will include Strix and things will be more automated!
The brief changelog for v1.4.9 LTS is:
Strix Music 1.4.9 has been released for both Stable and LTS, fixing audio playback and player control.
Sadly, the 'fixed' bit is more for Desktop than Mobile. The developer, Arlo, admits:
"I've spent a lot of time trying to fix mobile playback, but mobile runs an older browser and Spotify doesn't maintain support for it. We're at Spotify's whim when it comes to playback code, meaning it's unstable and can randomly stop/start working. I've done as much as I can."
Anyway, on your desktop PC (or Mac), head for the Strix Music home page, where you'll see the binaries (downloads) you need if you still want to play. It's unlikely to improve but hey, Spotify might change something at their end to improve 'Web player' compatibility. Most probably though, they'll simply drop support for such older browsers altogether and then Strix Music will be a no-go for good.
Oh well. As per my services rundown, lack of Spotify is just one of many that spell curtains for Windows 10 Mobile as a viable platform in 2020.