As it turns out, I had somehow been missing these errors in my log, which occur even when using the plain stonehearth body exported from voxelshop:
2016-03-11 17:45:47.028726 | client | 0 | renderer.render_info | stacked matrix leftArm size (31, 41, 31) does not match first matrix size of (4, 4, 6)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix leftArm pos (0, 0, 0) does not match first matrix pos of (21, 9, 12)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix leftFoot_0 size (31, 41, 31) does not match first matrix size of (6, 5, 12)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix leftFoot_0 pos (0, 0, 0) does not match first matrix pos of (16, 0, 7)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix leftShoulder size (31, 41, 31) does not match first matrix size of (2, 3, 5)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix leftShoulder pos (0, 0, 0) does not match first matrix pos of (20, 14, 13)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix pelvis size (31, 41, 31) does not match first matrix size of (11, 14, 23)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix pelvis pos (0, 0, 0) does not match first matrix pos of (10, 5, 12)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix rightArm size (31, 41, 31) does not match first matrix size of (4, 4, 6)
2016-03-11 17:45:47.038726 | client | 0 | renderer.render_info | stacked matrix rightArm pos (0, 0, 0) does not match first matrix pos of (6, 9, 12)
2016-03-11 17:45:47.048726 | client | 0 | renderer.render_info | stacked matrix rightFoot_0 size (31, 41, 31) does not match first matrix size of (6, 5, 12)
2016-03-11 17:45:47.048726 | client | 0 | renderer.render_info | stacked matrix rightFoot_0 pos (0, 0, 0) does not match first matrix pos of (9, 0, 7)
2016-03-11 17:45:47.048726 | client | 0 | renderer.render_info | stacked matrix rightShoulder size (31, 41, 31) does not match first matrix size of (2, 3, 5)
2016-03-11 17:45:47.048726 | client | 0 | renderer.render_info | stacked matrix rightShoulder pos (0, 0, 0) does not match first matrix pos of (9, 14, 13)
2016-03-11 17:45:47.048726 | client | 0 | renderer.render_info | stacked matrix torso_0 size (31, 41, 31) does not match first matrix size of (9, 9, 7)
2016-03-11 17:45:47.048726 | client | 0 | renderer.render_info | stacked matrix torso_0 pos (0, 0, 0) does not match first matrix pos of (11, 10, 12)