I tried many things. The issue got fixed after I made sure that all PCs are in the same timezone. I’m not sure what’s the relation between the timezone and GlassWire showing usage data.
Anyway, Since I had to install and uninstall and reactivate GlassWire several times today. Is there any way to know how many activations still available in my subscription? I want to make sure not to waste the number of PCs available in my subscription.