I have a new Spark install, when I click on "create" the screen goes gray, but the element that displays the key itself isn't visible. In the database, the key is created just fine. There is no error on the console, and it's the same on Firefox and Chrome. Key deletion works fine. Any help would be appreciated.
It's working here. Did you run npm install followed by npm run dev after you installed it? Did you install using the spark installer or using composer?
Finally found the answer, in php.ini, you have to have:
always_populate_raw_post_data = -1
set in order for it to work.
The warning about it goes out, which screws up the header, and the JSON isn't understood.