I just figured it out! So I hope this works for someone else.
Simple go back home when you discover your relics missing. You more than likely have a display case conflict like you have downloaded a cc object that also acts like a display case.
Save and exit the game once your sims are home
Open up delphys dashboard and delete all your conflicts. Please don't delete the ones that say ddbuild0, ddbuild01, 2 or 3. I think that's what they are called. They start with D and are number up to 3. If you delete these build files you will not be able to run your game! Eek! If you have a lot of cc like me you will no doubt have stuff conflicting with them. Just delete the highlighted objects that look like they have lots of numbers and letters if they do not come up labelled. Done? Awesome!
Go back to your game and play. Once you or your sims want to go back on a vacation, go!
Then go back to your relic collection. Still missing? I know it sucks.
But don't worry! Just put the display case in your family inventory and you will see you relics come off them, ditch your display case use either a shelf or one of your cc display cases and you can put your relics back in your collection rooms and attics
Yay! Happy simmimg!