It seems that the json output is missing the time key.
For example, if you look at spineboy-pro.json
The time following the "run" item has keys up to 0.8 ("time": 0.8), and its status is recorded.
And this is the EndTime.
In the file you gave me,
The key recorded in "04_walk_spec" that you are trying to play is
"time":0.6667
and it looks like there are not enough keyframes.