From PSU: “It looks like the recent World War Z 1.02 patch update is causing a rather nasty issue for some players.
World War Z, the co-op zombie shooter that is being hailed as the spiritual successor to the Left 4 Dead games released this week on PS4, Xbox One, and PC. Players across all platforms were reporting problems with the game such as connectivity issues and crashes. Saber Interactive assured fans that they were working on the issues and released a hotfix for PS4 that addressed the connectivity problems as well as an issue with the Lobo DLC bundle.”
Source: N4G PC World War Z Patch Update 1.02 Causing Loss Of Progress For Some Players