Ghost preview not showing in timeline when editing

[CCheukKa]

The usual "ghost preview" for when you're dragging or trimming clips in the timeline disappeared. Weirdly enough, it only happens in this sequence and no other. No amount of restarting Premiere or rebooting my computer helped. I have always been able to use Premiere normally and I haven't updated it recently.

Please help. Thanks!

[CCheukKa]

Update:

I figured out some properties of the bug. Whenever I deleted sub-sequences from my timeline, the preview is present again.