Continuous Thumbnails not showing

[Hrijoy Ray Patra]

I have enabled Continuous Thumbnails for my playback.

But it shows the thumbnails for a little while, then the thumbnails vanish, and when I pause the playhead, they re-appear; only to vanish again a litte later and the cycle continues.

Is this a bug?

How do I fix this?

I am also attaching a sample screen recording to show the problem