Designed a LPDA and I have a weird looking Gain Pattern

I have designed a 10 element LPDA and I want to achieve around 6-7dB of gain but I am getting an issue with the gain plot (see attached). It looks like there is some null on the PHI axis. I am feeding the antenna with a coaxial line and a lumped port at the end. I honestly have no idea why it is doing that... Hope someone on here can shed some light on this issue. Thanks!