After about a week or so playing on our server, the lights in one area of the world just "went out".  Areas with torches placed are pitch black - and it's not just a visual glitch, mobs spawn, etc.

This issue is only occurring in one area of our world, and the best I can tell it has something to do with:

1) Being near spawn chunks - the areas affected are all very near spawn chunks.  All y levels in this area are affected.

2) Some of the new blocks, such as glow item frames and glow signs, which have only been placed in the chunks nearby (friends that have bases many chunks away are not having this issue).

3) Something else weird that I haven't thought of

You can fix a small area by placing or breaking a light source (from what I can tell, anything that forces the game to recalculate lighting in the area will fix that small area).  This is of course unfeasible if you have an entire mine (or base) built with many torches/light sources already placed.

We spent awhile looking if there was a way to issue a command to the server to force the game to just recalculate the lighting in all areas to no avail.  I've also found no way to intentionally reproduce this.

(p.s. - to clarify, this is not specific to torch-lit areas.  Areas with lanterns and shroom lights have also been affected, but I've already fixed them so don't have screenshots to share)