Phantomical
From the forums > I tried switching from another mod that did this (Background Resources, from the KSP-RO people) to Background Resource Processing and all my frozen kerbals became lost and couldn't be unfrozen. They still existed but lost their ship assignments and stuff. I had to switch the mods back and go into the persistent file and manually spend an hour fixing it. I'm unsure as to the cause, but this needs to be investigated.