Adobe Premiere Pro not utilising CPU or GPU

Hi There,

I have a reasonably recent Ryzen computer which i built for video editing. My issue is that in Adobe Permiere Pro will only utilise around 30% max but generally sits around 20% on the CPU and no more than 3% on the GPU (i understand that GPU is generally only used for certain effects, transitions). Encoding takes ages! Slower than my previous build which was the ancient sandy bridge 2600k.

My build:
Ryzen 1800x @ 3.9 GHz
GA-AX370 Gaming 7
32 gb GSkill Flare X (2400 MHz) at 3010 MHz
GTX 1080 Ti
Samsung 950 Pro 512 gb (OS Drive)
2 x 2Tb Firecuda
Corsair AX760
Windows 10 Pro

Premiere CC 2018

I have tested this on numerous projects however as a test case I have encoded a 1 minute long Project which contains a mixture of 4k and 1080p slow motion footage with 2 LUTs, warp stabiliser (on selected shots) and a light grain applied. The encode settings are:

H.264

VBR 2 pass with a target bit rate of 50 Mps

3240x2160 (1.0)

29.97 fps

Progressive

Tried CUDA enabled and software only and doesn't make a difference to encode times

The encode takes a whopping 2.32 hours! Something doesn't seem right.

Any help much appreciated.

Cheers,
Chris