I think the synchros are bad on my 2011 Cruze Eco with 6spd auto gearbox.
I've heard people mention it happens more in cold than hot, but I noticed, if i accelerate hard in 3rd gear, the synchros get stuck, and suddenly jolt into 4th gear; which is why 3rd gear, even when hot, is not a gear I want to be racing in.
Luckily over 95% of my driving is in 4th to 6th gear, and 90% is 5th or 6th gear.
I hardly ever use 3rd gear, other than accelerating from a stop to 4th or 5th gear (which is the gear I'm most in in the city), or 6th gear when I'm going 40+ mph.
Even in traffic jams, I hardly ever use 3rd to 4th.
The traffic is either so slow I'm in 1st to 3rd,
or, it's not so bad, and I can continue driving in 4th to 6th gear.