Yes, true randomness exists.
What is Randomness?
Randomness is the part of an algorithm responsible of making its output value unpredictable. In modern computer science, we are still unable to accomplish true randomness. Every random-like algorithm is based on predictable variables, like the current timestamp (seconds elapsed since January 1st, 1970). Until today, we have been unable to design a function or a tool giving a true random output.
You can try to find an exemple of something not following a pattern in the universe, but you will not find it. There is only one thing that is random in the Universe. Conscious.
Assuming our universe could perfectly fit in a simulation, we can assume it may face similar problems as us, when trying to design computers or simulate the reality. From the Universe view point, what if Conscious is nothing else but the ultimate feature giving randomness capacities to its own algorithm?