At Star Wars Celebration this weekend Lucasfilm showed a short Rogue One teaser, but unlike other trailers there it wasn’t released online. The panel where it was shown was also a major panel, but it wasn’t even a part of the official live stream. There is likely a reason for this, and we heard about it pretty recently.
Last month a story came out that Paramount managed to get the MPAA to forbid Disney from promoting Rogue One until after the release of Mission: Impossible Rogue Nation. An exception was made for Celebration, but it appears that exception didn’t extend to people not at the convention.
While there’s no confirmation, it appears that deal is the reason why you didn’t see the Rogue One teaser officially released. They showed the logo and concept art during the Closing Ceremony (which was live streamed) but stumbled over an excuse as to why they couldn’t show the teaser there. Lucasfilm’s Pablo Hidalgo hinted at a release sometime in the future, which means we’re likely to see it after Mission: Impossible 5 releases in July. Another showing at D23 in August with a YouTube release seems the most likely place to do it.