Bar-chart - x-Axis labels being truncated to a single character

I’m running Grafana 10.3.1 on Docker.
I have an Influx query that returns the following data:

By default, when using a bar chart, the x-axis labels end up like this:

I want the labels to show the day and month in dd/mm format, so following various posts on this forum, I’ve set an override as follows:

Once done however, the x-axis labels all get truncated to the first character, plus an ellipsis, i.e.:

The override is definitely working; if I change the format to time:ddd, then the x-axis labels are updated to the first letter of the day of the week, followed by an ellipsis.

What am I doing wrong?

(Yes, I know the panel label says 30 day history and there’s only four days - I’ve only got four days of data so far…)

DD/MM is not time

date: DD/MM