Are you talking about the Planbuild mod?
I'm not sure which update broke it - it wasn't an official game update as it was working after that.
I launched Thunderstone and saw that one of the mods related to Planbuild had an update but I didn't look at which one it was.
After the update the mod fails to see or load any blueprints and isn't responding correctly when selecting objects to blueprint.
The thing is, looking at each of the required mods in turn, none of them show as having any recent updates - the most recent one was 3 months ago.
EDIT: I see on Thunderstore FractureValheim has created a mod called PlanBuildTemp to restore functionality. It does work but there is another bug whereby selected items still show as selected even after being subsequently deselected or saved.
SECOND EDIT: I have just checked again and PlanBuild has an update! 0.17.0 apparently fixes the compatability issues and the blueprint loading.
