I don't know if this is a real effect or not but "Zeigarnik effect" seems like a good name for a subjective feeling that I bet everyone finds familiar.

For example, an unfixed bug stays uppermost in your mind but the moment it's fixed I feel like it quickly fades - annoyingly so because sometimes you feel like you've just met the same problem again but can't remember the previous time.

And on a sadder note, unfinished conversations with people who passed away. I feel almost haunted by a couple.

https://en.wikipedia.org/wiki/Zeigarnik_effect