Achieving focus takes time or correct focus cannot be achieved during Live View shooting
Solution
If you use AF with any of the following lenses, using [Quick mode] is recommended. Autofocusing with [FlexiZone - Single] or [ 
Live mode] may take longer or correct focus may not be achieved.
Live mode] may take longer or correct focus may not be achieved.EF50mm f/1.4 USM
EF50mm f/1.8 II
EF50mm f/2.5 Compact Macro
EF100mm f/2.8 Macro USM
EF75-300mm f/4-5.6 III
EF75-300mm f/4-5.6 III USM
EF15mm f/2.8 Fisheye
EF-S18-55mm f/3.5-5.6
EF-S18-55mm f/3.5-5.6 II
EF-S18-55mm f/3.5-5.6 USM
EF-S18-55mm f/3.5-5.6 II USM
EF20-35mm f/2.8L
EF22-55mm f/4-5.6 USM
EF24mm f/2.8
EF28mm f/2.8
EF28-70mm f/3.5-4.5
EF28-70mm f/3.5-4.5 II
EF28-80mm f/3.5-5.6
EF28-80mm f/3.5-5.6 II
EF28-80mm f/3.5-5.6 II USM
EF28-80mm f/3.5-5.6 III USM
EF28-80mm f/3.5-5.6 IV USM
EF28-80mm f/3.5-5.6 V USM
EF28-90mm f/4-5.6
EF28-90mm f/4-5.6 II
EF28-90mm f/4-5.6 III
EF28-90mm f/4-5.6 USM
EF28-90mm f/4-5.6 II USM
EF28-105mm f/4-5.6
EF28-105mm f/4-5.6 USM
EF28-200mm f/3.5-5.6
EF28-200mm f/3.5-5.6 USM
EF35mm f/2
EF35-70mm f/3.5-4.5
EF35-70mm f/3.5-4.5A
EF35-80mm f/4-5.6
EF35-80mm f/4-5.6 II
EF35-80mm f/4-5.6 III
EF35-80mm f/4-5.6 USM
EF35-80mm f/4-5.6 PZ
EF35-105mm f/3.5-4.5
EF35-105mm f/4.5-5.6
EF35-105mm f/4.5-5.6 USM
EF35-135mm f/3.5-4.5
EF38-76mm f/4.5-5.6
EF50mm f/1.8
EF50-200mm f/3.5-4.5
EF50-200mm f/3.5-4.5L
EF55-200mm f/4.5-5.6 USM
EF55-200mm f/4.5-5.6 II USM
EF70-210mm f/4
EF75-300mm f/4-5.6
EF75-300mm f/4-5.6 II
EF75-300mm f/4-5.6 USM
EF75-300mm f/4-5.6 II USM
EF75-300mm f/4-5.6 IS USM
EF80-200mm f/2.8L
EF80-200mm f/4.5-5.6
EF80-200mm f/4.5-5.6 II
EF80-200mm f/4.5-5.6 USM
EF90-300mm f/4.5-5.6
EF90-300mm f/4.5-5.6 USM
EF100mm f/2.8 Macro
EF100-200mm f/4.5A
EF100-300mm f/5.6
EF100-300mm f/5.6L
EF135mm f/2.8 Soft Focus
EF400mm f/2.8L USM