Extend heatmap to range of plot even if outside of data range

If I send 1D data to plotly for a heat map and the range of the plot is greater then the range of the data the heatmap is extended to fill the range of the plot, e.g.:


But if I send the same exact data converted to 2D then the heatmap is not extended to fill the range of the plot (even when connectgaps is True), e.g.:

26 PM

How can I get the heatmap to fill the entire range of the plot area?