Put the summary of the bug you're having here

Upgraded our Minecraft Server Jar to 1.9.2 and restarted server (Using Multicraft)

Noticed several problems right away, which seem to be limited to a radius of roughly 100-200 blocks around the spawn-point for the world....

Some signs now corrupted with what looks like NBT tag / code markup:
from:
THIS IS
A SIGN

now looks like

("Text"," THI
("Text"," A SI

#2 *Nearly all Chests are completely empty (Though inexplicably a small number retained their full contents, no unusual patterns I could detect)

#3 ALL Item frames, and their contained items (Mainly customised maps) are completely gone

Reproduction is difficult as its a specfic world-save issue but if it helps I tried to revert older backups to get our items back and they are all doing the same thing, its as if the new release is interpreting something incorrectly in our world. (But only around the spawn point).

Its not a solution for us to just restart or revert our world back significantly as it has been in use for over two years and is now very important to several members of my group.

Im hoping others have seen this or may have insights - Im happy to respond with additional information as requested.

IMPORTANT POINT: This is not a duplicate report of the old bug regarding losing your items when downgrading to a previous snapshot. - No down-grading or experimenting with snapshots has been done, simply installed 1.9.2 as soon as it was released.

I have not found ANYTHING on the internet that suggests others are having this problem in the last few weeks.....

FINAL POINT: No mods installed, all pure vanilla and always has been....

many thanks