Strong magenta/red colour cast in the shadows

Im new to film scanning, colour film photography and NLP (not B&W which I develop and print in my own DR) Anyway I recently started using Kodak Portra 400. My first film was Lab processed and scanned using a Noritsu – I then set up my own scanning using a Nikon Z7, Sigma 105 Macro, Kaiser light source – see image:

I scanned the Lab processed negs using the above setup
and can get very similar results using NLP - considering I am new to this software I was very pleased with the comparison.
I then started using Cinestill C41 (powder kit) and i’m getting very pronounced magenta/red cast in the shadows. Its predominantly shadows and areas where there is already red in the image. My film processing is very controlled using the Cinestill TCS-1000: I use a 39°C pre-wash, then using the exact temp for dev. and blix with recommended times 3.3 mins and 8 mins with correct agitation as recommended. I then wash and use a distilled water and photo-flow.
I am thinking it must be my own developing C41 as the scanning and NLP in the Lab processed images is similar to my scanning process ??
Any advice, recommendations, insight would be appreciated.