Double check the code, especially if you copy and pasted anything. Make sure indents use tabs and not spaces. I had a lot of issues like this when copying and pasting compose files.
I started using nano editor (sudo nano docker-compose.yml) instead and never see this issue. Might be worth a try.
Love this app so much. Sonarr, radarr, BitTorrent, etc all accessible in nzb360
I never buy apps, but this one was worth it