The favicon logo in a Discourse forum keeps reverting to the Discourse Sketch logo. darkpixlz reported the issue, which only seems to occur on their end, specifically in Firefox. After trying different troubleshooting steps suggested by KhoiUSA such as clearing cache and checking in other browsers, the issue persists. KhoiUSA believes it may be a client-side issue on Firefox, while crcoli7307 thinks it could be a cache problem, possibly with the browser or ISP, and is trying to purge the CloudFlare cache to resolve the issue.
I haven’t seen this problem happen before, however I believe this might be an easy problem to fix. Before we go any deeper, you should verify the following:
1. Does anybody else on the forum experience the same problem? (If so, it may be #2)
2. Is this favicon reverting problem actually just cache?
3. Does the problem persist in other browsers?
4. Maybe try rebooting the server/rebuilding the container?
Seems like the error isn’t on the server-side, but it is on the client-side on Firefox. If you log into your forum with Google Chrome, will the discourse-sketch logo come back?
This seems like a bug on Firefox’s end, however, if this was a bug on Discourse’s end, then it should be addressed in the next stable update, since you seem to be running a beta version of Discourse.
Are you blaming my discourse install for not displaying you the favicon? 
Anyways I think it’s a cache problem, perhaps your browser or ISP is caching the favicon. I’ll try purging the CloudFlare cache for BlackIron.
