Connecting blocks appear as single

Anytime a block such as a double chest, fences, glass panes etc are placed next to each other, they appear as their individual state. Blocks in the distance also seem to have empty space in between each other, resulting in a greatly exaggerated grid appearance. My game also seems to have problems with placing blocks - if I place too many in quick succession a few will disappear as soon as I place them and return to my inventory.