I wouldn't worry about that missing ceramic cap, especially if the board is working fine and stable under load. And even if the board isn't working, it's probably due to something else.
Yes, these ceramic caps are important... but usually one or two missing won't break the bank. And even a few more missing might cause the system to become unstable only in some edge cases... but for the most part, they are kind of redundant... but still needed, because ceramic caps can vary quite a bit in capacitance depending on the voltage across them, the temperature, and age too, sometimes. So to make sure these don't become an issue, the manufacturer always installs enough to make sure the board will never have problems even if they start aging pretty badly. So that's the reason if a few go missing, you won't get any issues.