Chunk Size is shown as 1 KB in mongo db logs even it is set to 300 MB

I am running a mongo cluster. Chunk size set is 300 MB but for today morning it is showing me in logs taht chunk size is 1024 Byte. I checked in current op there also it is showing chunks of 1024 byte. I have check with monos and all config server chunk size is 300 MB there.

Please help me to resolve the issue as it is all of teh sudden bringing my shard set up down.