After reverting to a previous 'Oreokastro' segment in the Remnants of War campaign, I noticed that the game had not reset the memories that I'd recalled after that point. Additionally, the memory on the upper floor of the mayor's house was shown in yellow on the map, yet when triggered it neither turned the marker grey nor played any dialogue.

I'm worried this may affect my ability to attain the Memories of Oreokastro achievement.

The fact that memories had not reverted seems strange, as earlier on I'd reverted to an even earlier point in the campaign and all the memories reverted correctly.