Have you tried a UI reset? Maybe it's just a visual glitch. Just a guess...
What happens if you export your timeline as a drt and import that into a new project ?
ItsMeOverHere wrote:(One can't re-link if there is nothing there!)
You could import your used media into a new bin, select all clips in your timeline,
disable the conform lock and File > "Reconform from Bins...".
Be sure to only select the new bin in the Reconform dialog.