I'm using KDE Neon 5.19 which isn't too different from Ubuntu 18.04. Regardless, I have an old Raspberry Pi B (the one with just two USB ports and a full sized SD slot). I grabbed an SD card from a camera and tried to run the Pi imager on it to get my Pi running again. The imager completed without error.
Then I plugged it into my Pi, plugged that into an Android charger (Samsung) and into an old monitor that I've used with this Pi before. Nothing happens. It gets power, the light comes on, but the display says no signal. So then I check the card in the partition editor and it doesn't look like anything changed. The photos from my camera are still on the card.
What am I doing wrong? I choose the Raspian OS and the memory card is 32 GB.