Positive ovulation test before af?

The ovia app says i was supposed to have my period on the 4th. I always have bad cramps a week before my period and I thought i will have it because i had bad cramps on the 4th. But nothing... Now i am in CD30 and my cycle is usually 28 days.  
I took a hpt this morning but it was a BFN
I also just took an OPT and it's a faint line. How is that possible? Can this be an early pregnancy sign? Or have anyone ever seen a total negative ovulation test??
There are no signs of AF btw. 

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