Oh no! What operating systems/devices and browsers are you trying to behold the rat on? I can't recreate locally at the moment :(
Technical info for the curious: This issue is likely now resolved. Project is a unity project built with webGL, and by default it will try to set up a cache. The issue is a timing one - if the network connection is a bit slow for whatever reason or happens out of order, you'll get a message in the browser's console saying "[UnityCache] indexedDB database could not be opened". Since this is cache related, you can disable the cache in builds under Project Settings>Player>HTML5>Publishing Settings>Data Caching which doesn't make a huge different for loading in most cases, particularly with smaller projects.