Chunk Dissappeared after opening to LAN

Very bizarre, i loaded into my world and whilst my chunks were loading(it was taking unusually long this time) I decided to lower my render distance to see if that helped. Then as it was changing to a lower render distance(only went from 8 to 6 chunks) i opened my world to LAN to play with my brother. After clicking done, i proceeded to go to my base only to find that an entire chuck had been removed to a certain Y level and displaced to another chunk, that chunk disappearing altogether. Pics are included(sorry about the quality), though i cleaned up the chunks a little bit as i thought this bug would already be in the tracker reports!