While creating a block diagram I wanted to illustrate a switch function. I added the Electrical symbols to the icon panel and added a few different symbols checking that they would be clear in an exported PNG file. However the one I really wanted to use was the DPST switch - it displays nicely in the diagram and I can change the line thickness, but the exported PNG only has blank space. The DPST is the only symbol that does not appear to export, I tried thinks like diode, vacuum tubes and other switches.
I did find a workaround, if I select the DPST and click edit shape to look at its XML
then delete the <restore /> i.e.:
<restore /> ← delete this line
I am not sure if this is the correct thing to do, but it does allow the DPST to show up in the exported PNG.