Many others experienced this issue prior to the update and hoped they would correct it with the next patch. Unfortunately they did not. A major part of the utility of the app is being able to access the list of parts youve assembled, without our saves that renders that app broken for me. If they would fix this issue Ill change my rating. In the meantime, I recommend you write down your builds for future reference.
Update 4/7/16:
A recent notification sent out claimed that the saved build issue had been fixed and saves should load properly again. Unfortunately, this is not the case. My saves still fail to load. I can see all the save slots and names of my builds, but tapping them causes nothing to happen and my only option is to cancel. My 1* review will continue to remain.
Kevlar666 about GUNSTRUCTION