Negative ovulation tests but EWCM?

At the end of the day on CD10 I started having EWCM. I took a cheap strip ovulation test and it was really close to positive but not quite there yet. The next morning I took a clearblue advanced and it was the empty circle. I’m now on CD13 and still having EWCM but continuing to get the empty circle.

Since I went off the pill in July, I’ve been ovulating two days earlier than the month before. Last month I ovulated on CD17.

If I’m having multiple days with EWCM shouldn’t I at least be getting the flashing smiley? Has anyone else experienced this?