The Issue:

When setting the ray tracing render distance, anything greater than 12 chunks seems to have no effect.

Reproducing the Bug:

(This way is the most obvious.) With a large amount of glass around you, change the ray tracing distance settings. The amount of glass that is affected by ray tracing won't change past 12.

Expected Outcome:

More glass blocks should be properly see-through as distance increases.

Observed Outcome: 

Past 12, no more glass blocks become transparent.

Tests for Different Settings (see the glass blocks in the background):

8 chunks:

12 chunks:

16 chunks:

24 chunks: