I was playing well known Night of Knights on Nasya's Insane difficulty. After FC'ing the map, I wanted to see the local replay, but it was gone. I replayed the map, FC'ing again. I immediately checked for replay, it was there. Restarting osu made the replay disappear. What's more interesting, the previous non-FC replay are still there. I had no issues with my internet connection whatsoever.
https://ibb.co/m9E8ee
https://ibb.co/bYroee
osu! version: 20180811.2
https://ibb.co/m9E8ee
https://ibb.co/bYroee
osu! version: 20180811.2