I have a date field ("Completed"). It shows up in my main form

as well as in my list of fields.

But it is not available as a column for new reports.

">https://d2r1vs3d9006ap.cloudfront.net/s3_images/1682071/RackMultipart20171214-59520-1l8zrov-2017-12-13_18-57-38_inline.png?1513220398">
It was available yesterday, but not today.
Any explanation?