I have tried this SID 3 different times and got a different outcome every time. Here's how it was programmed in:
I've included videos below of each attempt, the most pertinent probably being number 3, which reproduced what I described in the original post. (Edit: these videos seem to stream horribly, I'll try reuploading them shortly).
Attempt 1:
Aircraft generally seemed to follow the correct route as drawn on the chart, but climbed incredibly slowly for some reason, resulting in terrain and gear warnings, so I decided to restart. Closest to the one shown by @skiselkov.
Attempt 2:
Aircraft loosely followed the correct route, making the correct turns at the correct altitudes, but took some quite sharply, so deviated from the mapped route. Maybe that's okay, I'm not sure.
Attempt 3:
Here the aircraft turned in the opposite direction to that on the chart and the FMS, as I described in my original post.
I didn't vary anything between the 3 attempts, other than tiny differences in my inputs and timings. Please excuse poor FPS and strict adherence to checklist while I was juggling a few things.
Maybe I did something wrong, if so please let me know.