Torches not giving off light!?

I’ve been playing on a Minecraft Realms with some friends for about a month now but lately some of the older torches that we have places are not giving off ight like they used to.

Does anyone know why?

If they are destroyed and replaced they’re fine and any new ones placed work well, but the ones that have been there don’t give off enough light to span areas lager than the block it’s placed on.

Is that a chunk loading error? Should I wait for new patch?