@elliot Thanks for your help!
*I’m not using any hooks or filters that would affect ACF.
*Debug mode is currently off
*It wasn’t an error during save. I just updated to 4.2.1 and then went through the site to see if anything broke and noticed that all the relationship values were gone.
Other potentially unusual things:
*Windows Server
*The Relationship is a custom post type to another custom post type (Projects have many Wood Species, Door Styles, and Finishes). I believe everything still existed post-update, it was just the relationships that disappeared.
