What is the required format for DateTime values when importing DevOps Work Items using CSV?

Question

To help automate the creation of a monthly work set we're attempting to take the 'January' set of User Stories and Tasks, adjust them for February and then import them using the CSV import in DevOps.

We have added the 'Due Date' field to the Task record in our modified process so that we can track weekly deliveries, using the Microsoft.VSTS.Scheduling.DueDate field used elsewhere.

Everything seems to be fine with picking up parent items and assigning users but no matter what I do I cannot get the importer to accept the datetime format for the Due Date field.

I started off with the format from the 'Export To CSV' functionality (US Format, 12 hour clock) e.g. 2/3/2022 12:00 PM and the importer reports The value for field 'Due Date' is not of the right type.

I have since tested about 30 combinations of date and time formats to no avail; UK (browser locale), US and universal formats and it's the same error every time.

I suspect that there is a very specific format that I have managed to miss so far, as I see the same error when trying to set a Target Date for a Feature, which is in the default Agile process.

Can anyone share a working format, or insight into whether it may be affected by my region or the region of the DevOps instance?