z5 and into z10 ish (where OSM takes over)
oddly, z4 works.
encoding issue in one of the labels starting at zoom 5?
z4 files display at z5 and z6 with a file ref swap.
problem seems to be in the z5 and z6 and up files themselves.
This is related to Dymo failing to force "population" to be type Number instead of String when no value is present in the input txt file.
Solution is to use the Dymo generated "font_size" attribute instead of population grading again.