I spent all the night with Display.captureScreen on Android. It looks that Display.captureScreen (true) does not save correctly to Album on Android devices. It can save just one screen to Picture folder with name "corona_image.png" while it should be able to save pictures with different names (picture1.jpg - picture10000.jpg).
It works OK on simulator and I did not forget to set WRITE_EXTERNAL_STORAGE permission. Without that permission it does not save anything.

I tested it on many daily builds and many Android devices - the same results. Quite a big problem for me, I need this function for drawing app for kids. Any idea what could be wrong? Did anyone succesfully use this function on Android?

This is a known issue - only one file can currently be saved this way on Android. (It overwrites the previous one.)

It's being looked at.

I could create my own gallery which would look for pictures at system.DocumentsDirectory.
I can capture the screen with display.captureScreen and then save with display.save.

But... Display.save downscales images to 512 pixels!!!! Well, it could be enough two years ago but Corona is not only a tool for low resolution phones but also for high resolution tablets!

Edit: Good news. Downscaling to 512 pixels with display.save is not an issue on all Android devices. It looks that it works without downscaling on some devices.