I search for messages timestamped from any day in 2016 to any day in 2017 and all the search results are from 2018.
The UI clearly shows Date: Select range From (some day in 2016) to (some day in 2017).
How do I fix this?
You can do that with Instant Search as well, although it might not be directly obvious how because searching between specific dates requires a specific notation.
If you’d like to type your query directly, then you can type the following in the Instant Search field if you want to search for emails that have been received in the month of April 2018:
received:4/1/2018 .. 4/30/2018
It is important that you type the correct date format of your computer. So it might require you to type the following instead:
received:1-4-2018 .. 30-4-2018