From a new thread on Reddit, NTT replied to someone:

"Reviewing the information provided the source of the packet loss is likely due to an AT&T and NTT congested peering point. While there were no issues present in the traceroute provided, I can see that the return path for your traffic would likely be traversing a known congestion point in LA where throughout most of the day you would be experiencing packet loss for this source/destination combination. Unfortunately the issue you are experiencing is not technical in nature but instead more political. Both AT&T and NTT are aware of the situation however due to NDA's we are unable to discuss specifics as to when an increase in peering capacity would be initiated. This issue has already been escalated to the highest technical levels within NTT to helpalleviate the congestion as much as possible however we're unable overcome the root of the issue which is a lack of capacity.Due to NDA, we can't disclose any specifics. However, we have been taking and will continue to take technical steps to remedy the situation to the extent possible at our side."