The horse making the jumping animation but not lifting off the ground seems to be an issue for me too. While I'm naturally irritated by this bug as I am by most bugs, I am glad to see it is not just skeleton trap horses as I thought (because they were the first horses I tried to ride since the new snapshot).
The hopper is not locked, no redstone is anywhere near it. The hopper has no chances to be full as it is connected to a large chest that is cleared out regularly. This is not an "invalid" bug.
This goes for Skeleton Trap Horses as well. If one is encountered and all of the skeleton riders are defeated, you can mount any of the 4 skeleton horses and put a saddle on them but cannot control them at all.