Do you have a version of AdBlock installed on your browser?
We have come across some versions of AdBlock occasionally not allowing users to access certain models or explores that have “ad” in the name. You can test whether this might be the problem by running the query in Incognito mode, or in a different browser.
If you whitelist looker.com in your AdBlock extension, this should prevent this from happening again.
For more information on how to whitelist domains in AdBlocker, checkout this YouTube how-to video.