I was doing Instructor #5 (Sauromaugue Champaign). I died, warped to HP, and went to Adoulin to farm a gnatbane for a friend. After that I changed jobs, went back to the burrows via the warp npc in Upper Jueno, and traded him my grimoire. On the selection screen, my only options were Adjunct #1 through Researcher #1... All of my progress was gone. I can still buy the Rewards for the areas I had clear, however.