I've put a text box in front of a chart, but when I click on the chart
for whatever reason, the text box disappears.

When I click on any area outside of the chart, the box
appears again.

Yes, of course I cut, select the chart and paste the box onto the
chart; and same error.

The chart width is from column A to Column Z.

If the text box is in column Q or before that column, the text box is
displayed. But if the text box is moved to column R or after that
column (in the chart), the text box disappears.

Is this a Excel bug?