Whilst i understand the frustration, i think that you,
@SDEV , are being rude and unhelpful.
The issue that is at hand only affects (as i understand) a very small portion of people (myself included) - and these people are ones with hackintosh setups (Going into the whole hackintosh scene, you knew full well that not all things ill work 100% correctly).. So for CO devs to be able to replicate this issue will require a similar build to us (compatible parts, nvidia GPU, drivers, kexts and patience), and then will need to runs tests and check logs to try and diagnose the issue, create fixes, QA checks (so it does not effect/break anything else), then release the patch. Not a straight forward task at all.
Now, saying the game is unplayable is a bit of an exaggeration, as i have been playing the game (using mods, workshop items etc fine), and adapting to the diagonal line. Yes it is annoying, but hey... i will put up with it to play such a great game.
So from what i can gather, this new issue has only occurred after version 1.5 update in December - so there is hope they will be able to rectify the issue at some point, and i believe that
@co_emmi and the developers are working on the issue, and will hopefully solve it soon.
Finally, CO keep up the good work, and i am looking forward to the Mass Transit expansion pack, and will still play it - with or without the diagonal line.