Is it to do with your settings? I think I had this issue when I had low settings because my pc was a potato, now I have a sweet potato!
My thoughts on what may be causing this : Try changing texturepacks, sometimes it could affect certain items and blocks, even if they were fine before. Slow map loading Render distance causing a part of the map to not load. Client issue (?) Bad internet connection causing the loading to be a little slow. Maybe minecraft wants you to take a break and get some fresh air.
not the texture pack or the render distance, not internet cos i have good internet. i loaded 1.8.9 (was on 1.8.0) and its fixed....so it must be minecraft 1.8.0
Ohh wow i thought it was clear that i meant the latest version of 1.8 ill be more clear next time. Maybe lock the thread now? @zRinne