Lumetri Errors

Hello, thanks for your time.

I am running Premiere Pro 2020 v14.0.4 on my Macbook Pro (2014, 2.2GHz Quad-core i7, 16GB mem, GFX Intel Iris Pro 1536 MB) and since these last two PP updates I have encountered some problems with Lumetri Video Effects.

Finished products look fantastic on the timeline, using Lemitri for brightness and contrast tweaks and adding some filters like Kodak Soft in Creative. However the exported MP4 is randomly displaying glitches and colour effects, different on every export, I restarted and it was different but still loaded with glitches / artefacts and unusable. By removing the Lumetri on the video clips the sequence does then export perfectly. 

Any ideas? Lumetri does wonders for my footage, need it back! Thanks!

John