Since maybe 3 or 4 months ago, I’m regularly (but not every time) finding a daily post from one particular mailing list landing up in in my junk folder. I’ve been on this list for many years, and no such issue until now. Been using SpamSieve with Apple Mail for years too.
So far I’ve tried:
repeatedly train good
checked whitelist and confirmed that the sending address is in it
checked blocklist - found sending address in there too - deleted it
Is the whitelist rule checked? Is Use SpamSieve whitelist checked in the preferences? If the answers to these questions are Yes, then the message is not going to the Junk mailbox because of SpamSieve. (Also, SpamSieve normally uses the Spam mailbox rather than the Junk mailbox; messages in the Junk mailbox are likely to be there because of Mail’s junk filter or a server filter.) Please see this page for how you can figure out what’s causing this.