I had the same problem in Windows 10 with the desktop app (SlingplayerDesktop-184.108.40.206.exe) and solved it by simply uninstalling the program via the Control Panel and reinstalling it from my Download folder ("Repair" didn't work). CAUTION: You need to remember your email address and password. After re-launching, you'll be asked for that info. Hope this helps.
Anyone experiencing an issue with the desktop app today? It just hangs right when it tries to load the first advertisement.
I wonder if Chrome ending Flash support has anything to do with this? I know the desktop app uses Chrome (you can tell by right clicking in the main video area, and click About)
Windows 10 with M1 running desktop app v.220.127.116.11