I am having similar problems, getting legit emails ‘soft reject’, and they don’t resend (I am pulling them off the server with the connector with IMAP. I also get ‘soft reject’ from domains that are whitelisted in From Domain. Not sure how that can happen, but it is.
The file /etc/rspamd/override.d/greylist.conf does not exist, I tried creating it and adding the single line enabled = false; and restarted rspamd and I continue to get ‘soft reject’ emails that are never resent.