Problem
When I try to update the blockdata of a sign using this code:
/blockdata ~ ~1 ~ {Text1:"{\"text\":\"Test\",\"open_url\":{\"action\":\"run_command\",\"value\":\"https://www.google.com/\"}}"}
it gives me no error but refuses to let me open the link, there isn't even a prompt. Amazingly, the run_command action still works.
Replication
Update a sign's blockdata via /blockdata and add the click event "open_url" to some text followed by a website URL as the value. There is example code above.
You have the wrong syntax (but seem to know it?), what do you expect to happen? This is all working as intended.