Craft 3 entries "before" not working
This is down to lacking documentation. Before/after are supposed to take  "DateTime|string" as a parameter in the ElementQuery. The format is not documented.

Use "Y-m-d H:i:s"

{% set start = "2 months ago"|date("Y-m-d H:i:s") %}




Behind the scenes in building the query the CMS was replacing any dates I sent through with "2017-12-31 11:00:00" (no idea where this came from). After realising this I spelled out the before/after in format "Y-m-d H:i:s" and the dates started working.

Pixel and Tonic - Can you please update the docs to include the available date formats - or at least throw an error if it's not valid.