ILR Data Mismatch.

They said in a webinar not all that long ago that this sometimes happens if there was a delay in getting the new DAS record set up, but you'd already processed the progression on the ILR, causing a data lock because it tries to match to the current DAS record. Supposedly you should still get paid, and this can be ignored/will disappear.. just not immediately. I'd recommend checking over the next couple of months to see if you receive any funding. If so, you can essentially ignore it. If not, give the service desk a call. 

Thanks for the reply Ben! I managed to speak with the help desk earlier and it's been passed to Technical Support Team to investigate further. Hopefully resolved soon