Big Bad Bug with Castle Samurai

This has happened to me twice now, first at Yura, now at Amagasaki Castle. Last night I killed the 5 Samurai at Amagasaki. One on the East, two at the top inner wall, one on the north east outer ring, and the last one who walks around the castle. All 5. I did it fine on other playthroughs, but I had to log out as I was going up to the chest, because my dog needed to go out and it was late. This morning, I start off going up to the chest, and I notice that it says I have only 4/5 Samurai. I checked all the locations again, no Samurai in the entire caste.

Twice this has happened to me! The first time was at Yura Castle, the guy on the north just wasn't there, and no matter how many times I go back on that playthrough, he's never there.

This is incredibly frustrating. Is there any way to fix this?