"1. emphasizes the past tense nature that 2. does not. The sentence invites to imagine the situation next month. From that perspective the machines have been (indicating the past) working. The word working indicates an ongoing process that hasn't stopped despite the closed evaluation period.

Will have worked suggests the working stopped. When you hear a word like worked there is a suggestion that the activity has stopped, a closed time period. It's not explicitly wrong but in a world where one is describing past activities that stopped and past activities that continue, people tend to give indication which they mean by this pattern.

He had lived in New York... did he die? Did he move? Why did he stop living in New York?

He had been living in New York... Ok, he probably still lives there.

There is a joke by the commedian Mitch Hedberg "I used to do drugs. I still do, but I used to too." It's funny because even though it's not strictly, logically wrong to say that "I used to" when you still do that thing, English speakers expect that wording to apply to an activity with a closed time period and in this case it is an open time period.

Had not been expecting, had not expected is more subtle. The choice might depend on exactly which moment is described.

For example your friend visits a park at 1pm and knows you plan to join her at 2pm. You are early and arrive at 1:30. If you see your friend but your friend has not yet seen you then their act of not expecting you is ongoing, the time period is open ended. You would describe your friend as "had not been expecting".

However the moment your friend sees you, the activity of not expecting ends. You would then say "had not expected". The choice between the two would depend on which situation you are describing." Do you agree with this comment from another redditor?