It's been like that on and off for a couple of weeks. I had it two weeks ago , then it cleared but then refused to run the futher diagnostics until two days ago. Seems that it is literally suck it and see when you run it.
I have also found that using chrome the download is fine but upload is always 12/13 where other sites such as speedtest.net show an accurate 18. I haven't checked using edge mainly because I can't be ar**d anymore since it is a BTW speed fault.