I don't understand fully what's happening but I play on my realm with my friends and I just recently started to ride horses on this realm. After I ride a horse for a certain distance (maybe 40-60 blocks idk), I can't go forward as if I am running into an invisible wall. If I get off my horse I still can't go forward but my horse will walk forward by itself and can go past. I brought my friend over as soon as this happened and he could walk straight ahead of this "invisible wall" with no issue. I found the only way in order to go beyond this "wall" was to rejoin the realm. This happens in any direction and at any coordinate. Today (like 10 minutes ago) my other friend experienced the same issue and I really think that this issue should be brought to your attention. My wording probably isn't the best but I hope you can sort-of understand what I mean. Please look into this issue as it is very annoying and frustrating.