On a few occasions it has become difficult to engage 5th gear. The problem is not consistant, happens at different times of day and engine temp's. Speed at change does not have a effect. Have to hold gear lever and release clutch to engage.
Problems selecting 5th gear with manual transmission. on 2008 Chevrolet Aveo
I have had to replace synchronisers and gears to correct this on these transmissions. Your vehicle has a 5 year, 100,000 mile powertrain warranty, so it may be covered at no cost to you.