Thanks for writing in!
Usually, when you see 100% packet loss, but are still able to access the service as normal, this is due to a router being configured to ignore or drop TTL expired packets, which are what PingPlotter sends. You can check out this link to see a bit more information on why you may be seeing this:https://www.pingman.com/kb/8
On a side note, we decided to run some traces to these services as well. We did get the same results as you, which does point to a possibility of our TTL expired packets being dropped due to security concerns or load reduction. We did, however, adjust to use TCP packets sending on port 80 (mimicking normal HTTP traffic), which resulted in a successful trace to all of the listed sites. If you change to TCP port 80, does this work for you?
Let us know if you have any other questions!