Delta Drive, Delta Trust & My Drive · Linked folders and copies
Why did my synced folder stop and turn orange?
Short answer: A sync stops before a big delete — over 50 files, over a fifth of the folder, or every file changed at once. Open Sync settings… and choose Sync anyway (removed files go to the Trash) or Keep paused.
It stopped to protect you. If one sync would remove more than 50 files, or more than a fifth of the folder — or if every file on one side changed at once, as restoring a backup can do — it stops before removing anything and the folder's badge turns orange.
Right-click the folder and choose Sync settings… to see what happened, then choose Sync anyway (anything removed goes to the Trash, where you can get it back) or Keep paused.
A folder that isn't there at all — an unplugged disk, a folder you moved — is never treated as "everything was deleted"; the sync simply waits until it's back.
See synced folders.