I no longer have 19.1.0 installed to test, but it is working here on 19.1.1 with Windows 10.
I don't want to suggest resetting preferences until a Mac user can confirm on a similar system to yours that theirs works (or doesn't). You could try setting a different level of GPU acceleration (Basic/Normal/Advanced in Preferences > Performance. You will need to start, or open, a new document after each change to see if it makes an impact
The pen tool won't work for me if my canvas is rotated (using R).
I am running PS CC 19.1.0 and High Sierra 10.13.3
What is your UI scaled to?
What is your screen resolution?
Have you tried increasing the path thickness and changing the colour?
Like Dave I am using 19.1.1 on Windows 10, and have no issue. For a long time Adobe told us it was difficult to do anything about the way workpaths showed because of the way Mac systems used blend modes. With you being on a Mac, I wonder if that is relevant to your issue?
I am on a 27-inch (5120 x 2880) using a Radeon Pro 580 8 GB card.
I noticed Dave's post and updated to 19.1.1. This seemed to fix the issue at first. Now though the path seems okay at first, then has problems further in, where the last anchor point or part of the path disappears from view (when the canvas is rotated). I was able to recreate the problem and posted a video below.