Here is a video where the text is being rotated at different angles. You can see from the flickering that at certain angles the text just doesn’t get drawn.

 

And here is a video where I’ve created a bitmap of the text drawn unrotated and then I draw the bitmap rotated at different angles. Which works:

 

I am drawing the core text within a path rather than from a point and I think that is the issue. I have seen in other situations when drawing multi-line wrapping text in a a path that is a column then if the drawing happens while the context is rotated then at certain angles the line wrapping for the first line of text behaves oddly.

I get exactly the same behaviour on iOS as I do on OS X.

This is definitely an issue of drawing the text within a path, drawing the text from a point works as expected.