Most common notchiness twins owners with MT gearbox observe - is harder to get into 2nd when cold. Most ignore, as it goes away after 5min of driving.
Now if it's hard to get 2>3 .. imho it's something else. Unfortunately i don't know well, what it might be and how to fix. One thing i'd try, is to adjust plate that positions lever at right places .. was it reverse lockout plate? If that doesn't help .. while oil change is relatively simplest/cheapest thing to do, so worth trying for that reason, but i somewhat doubt if it will fix (after all, other gear engagement is fine?), i suspect something wrong with gearbox of this specific car. But as it's 2018 .. there should be warranty, no? Make dealership fix/replace it. Disassembly of gearbox to inspect synchros/gears and-or replace will take long time and will cost a lot. New gearbox costs extraorbitant sums (IIRC ~4K?). If warranty is not an option, i'd also explore to get used gearbox (600-1K), as imho it would be cheaper and quicker then disassembly/overhaul/cost of parts/time to receive them