It never should have been, but I believe you 
I’ll fix the issue of it removing when CDH is disabled.
Everything worked fine last nite with download handling turned on. I have no idea how it got turned off. The only thing different I’ve done in the last few days is run CCCleaner and I don’t see how that would turn that switch off. Oh well,it’s working now so I’ll stop worrying about it.
I have the exact same issue, I never had CDH enabled but Sonarr suddenly started removing downloads from the Sabnzbd history, have it enabled now with remove set to no, hopefully this fixes it.