Weird render issues in FCPX

Getting this weird rendering issue in FCPX 10.4.3. Doesn't happen on the entire video and doesn't even happen on any particular effect or transition. It first happened on a cross dissolve at the beginning of a video but also occurs at a random point too.

OS: Mojave 10.14.2
Processor: 3.7 GHz Intel Core i7
Memory: Corsair 32GB 2666MHz DDR4
Graphics: Sapphire Pulse Radeon RX580 8GB
MoBo: Asus Z370 Prime II
Lilu Kext

I assume it is some issue with the graphics card but hoping someone can help me identify the issue and fix it. Any additional info required just ask.

Thanks.