the metrical strength features in note_features.py return four attributes:

"beat_phase",
"metrical_strength_downbeat",
"metrical_strength_secondary",
"metrical_strength_weak"

metrical_strength_downbeat and metrical_strength_weak return 1.0 in the presence of a downbeat which seems wrong for the latter, line 1066 is probably the problem. A bit of documentation on each feature is also missing (what is secondary, what is weak, does it work for triple meters?).