unexpected curvilinear image on 17mm lens with BMPCC4K

Hi, just got a BMPCC4K to replace an Olympus PenF for recording art classes
My Olympus 17mm f1.8 MSC lens gives a rectilinear image on the PenF, but fitted to the BMPCC4K gives a noticeably curvilinear image?
I understand that BMPCC4K has a crop factor of 1.9 rather than the 2.0 for usual MFT sensors, is this why I'm seeing a distorted image with the 17mm lens on the BMPCC4K but not the PenF?
If I need to buy a new lens, will an 18mm+ safely get me back to a rectilinear image by the math below, or is there something else I'm missing? (distance from subject is the same, approx 1m) Thanks!
17mm x CF2.0 = 34mm equivalent
17mm x CF1.9 = 32.3
18mm x CF1.9 = 34.2

Looking at reviews of your lens, most people are satisfied with the lens but some are not impressed with the sharpness. One review did comment on the distortion. The reviewers don’t mention on which camera they are mounting the lens. It may be most are Olympus cameras. Some mFT cameras such as Panasonic correct for their lens distortion in camera. Perhaps Olympus does that too. If you are using DaVinci Resolve, there is a Lens Correction feature in the Edit page. That may help.

Olympus also makes a higher quality Pro series of lenses that likely perform better such as their 17mm f/1.2 Pro lens:

https://www.bhphotovideo.com/c/product/1366998-REG

This is what the Olympus 17mm f1.2 looked uncorrected.

Bildschirmfoto 2024-03-10 um 16.09.07.png (665.77 KiB) Viewed 372 times

Here you can find more https://opticallimits.com/category/micro-four-thirds/
For the uncorrected file you must click the RAW tab.

Thank you both for the very helpful information
Once I understood what was happening the sharpness of the Olympus lens did seem disappointing, so I bought a 25mm Meike and am now much happier all round!