This has happened several times before. On opening my lesson for today I yet again saw that my ranking of 63% after yesterday's lesson and many before has been lowered to 62%. This is very discouraging and is innacurate.
They are a total gimmick. Ignore them. At level 14 there is no way on Earth that you are even close to being 63% fluent! You would be lucky to be 20%.
There have been many complaints about the Fluency numbers. They are not accurate at all times. Try to ignore them and go on with your learning.
They're not accurate in any way at any time! Because what they are measuring is not fluency in a language at all. Just how fast and frequently you tell the computer what it expects to hear. Hence you are likely to have a higher hit rate when that figure is based on a lower number of vocabulary/sentence items 'taught' - it could almost be inversely proportionate to fluency!