I tried to load the datahub.json from #62, https://wangcluster.wustl.edu/~fanc/browser_datahubs/holtzman_ATAC_group/holtzman_ATAC_group.json

However, the group tracks seem appear be empty after loading it (I tried it on mm10 and mm39):

Interestingly, when I hover over the tracks I can see that data is present. I also noticed the y-axis on the left-hand side is not annotated with a min and max value.

Also, when I change display mode to heatmap, I can see some data. In the screenshot below, I did this for the first track: