I tested Roon - Jazz Groove FLAC for you.
On Roon (Core) 970 Windows 10 Pro 21H1 in Lumin Hong Kong office, I added all five FLAC Jazz Groove in PLS format to My Live Radio. All five streams play normally for at least 15 minutes from Roon to Lumin. Signal path confirmed they are FLAC 16/44.1.
Then I stopped Roon, installed Surshark Windows VPN and connected VPN to Australia - Perth. Browsing whatismyip.com confirmed my IP address is in Perth. Then I started Roon and played the Jazz Groove FLAC from My Live Radio again. It basically still works for me, but loading times are slower and inconsistent. There was one time when I could not play Mix 2 FLAC, but it succeeded on second try. I also saw it stopped twice during playback.
When reporting to Jazz Groove, you need to find the regional server link in the format of:
https://audio-edge-xxxxxxx.radiomast.io/xxxxxxxx?token=xxxxxx
This URL is the result (after server redirection from the Stream URL (not PLS)) seen from a suitable browser on a suitable platform. I think Firefox on Windows, Firefox on Android, Microsoft Edge on Windows, or Chrome on Mac OS should work. Safari browser does not work.
(Note: Using VPN with Roon tends to be problematic.)