If you migrated Survival Game Kit to another project you may have an issue with building parts not snapping. To fix this go to the Project Settings and then to the Collision tab.
Then click the Trace Channels drop down and click New Trace Channel, name the Channel Grid and set the default response to Block and click Accept.
Now click the New Trace Channel button again and name it Weapon and set the Default Response to Block again and click Accept. Once you are done it should look like the image below.
Next click the Preset drop down below the trace channels, and click the new button.
Then copy the settings shown in the image below, make sure the name is set to DeadPlayer.