I’m trying to generate a Flight plan to EGAC from EGLL and it works perfectly and loads the SimBrief page then it diverts back to the ICAO section which is normal but from there it just doesn’t load no blue bar or anything.
Could you attach a screenshot of what you are seeing so we can better assist you!
I have had this happen to me. I usually spam the “generate flight plan” button until it loads in. If that doesnt work then you can always use simbrief then copy the XML file I believe unto FPLTOIF.