What are you attempting to achieve?
Find out what is going on What is the issue? (Keep it simple and clear - Include screenshots/videos/GIFs if possible)
My issue is that parts above a certain height randomly disappear with no trace, for example this part:
How high is the Part?
Is it Anchored? If not it’ll fall down and if it’s CanCollide false then it’s going to fall through anything underneath it.
Have you tried testing it with the Run setup (F8) while looking at the Part? If there’s a script that is deleting or moving the Part you may be able to see it a bit better rather than waiting for the game to load and your character to load in, which takes a few seconds.
Have you also tried Inserting a new Part into the Workspace and Anchoring it as well to see what happens?
Also i would check if you have added any new models from the studio toolbox that maybe contained hidden scripts… also check output for errors and give us anything suspicious looking?
One more thing… since u mentioned it was happening to new parts… make sure ur parts are Archived and all the regular settings are checked off… u might have changed a default setting without realising.