In macOS Mojave, tapping the space bar to open a picture in Viewer does not work. I have tried the fix in this thread: Keyboard shortcuts (spacebar) no longer works in Photos on Mojave
However it only works to open, not close. I can not comment or post on that thread so I’m forced to open a new one.
Has anyone found a fix that gets close to work using the Space key?
As of Mojave 10.14.4 – Photos has changed back to the normal use of the space bar to preview an image. So if your have not upgraded yet, do that 🙂