I had this issue with the linuxserver.io image, but I don't run unRaid.  For myself, the issue was having the "MONO_TLS_PROVIDER: legacy" environmental variable enabled.  As soon as I disabled that and restarted the container it began working again.    I don't know if that's your issue, but since I fire up radarr with a docker-compose file I simply commented out that line in my "environment" section and did a docker-compose restart and all went back to normal.    I just opene