FINALLY a positive LH surge

I've been using both Wondfo ovulation tests and Clearblue Advanced and I got a peak day starting Saturday on Clearblue and it has stayed peak through today, but the Wondfo tests (and even a couple first response tests) were negative.  I finally got a very positive Wondfo test this morning, so I'm wondering how they can be soooooo many days apart?  I haven't had a temp spike yet, in fact I had a slight drop yesterday and today, so I think the Wondfo tests are correct. I am so happy that I stuck to testing with the other tests, though. So frustrating!