Other plugins cause such issues. For example GriefPrevention makes them disappear: https://github.com/randombyte-developer/holograms/wiki#griefprevention-flags
In your case it is most likely also another plugin.
Start by removing plugins that interact with the world heavily (protection plugins). If the issue still persists, try binary searching for the plugin that causes problems:
Make a test server, and install only half of your mods in it, plus SpongeForge. Does the problem persist? If so, the problem mod is in that half; if not, it’s in the other half. Now you know what half it’s in. Clear the mods folder, and put half of that half in the folder, plus SpongeForge. Same procedure, and now you know what quarter of your mods the problem mod is in. Do it again to know which eighth, and so forth until there’s only one mod aside from SpongeForge. Through this process you can efficiently narrow down what mod is likely causing your problem.
Taken from the Sponge discord bot