got the same problem, vanilla ect. and i realized it way to late (because i load the game in the background because it takes so long to start up from a non ssd)
if i load any of the the last 10 savegames a message pops
"achievements are disabled"
nothing else.
is there any easy way to enable them again or fix this issiue or prevent it from not happening?
i don't want to unlock my achievements with an achievement unlocker/mod wich is recommeded in some forums :/
if i start a new game or load a month old save game it does not happen, only in my actual campain within the last month since i collected the banner.
if you need any files (savegames) or further information let me know it