It looks like server and clients sometimes load mods in different order. This seems to create an issue when multiple mods are loaded that attempt to override the same thing, such as the EditorModeEdit.et prefab, as demonstrated in the attached video, where the entity browser spawns different entities than the entity being requested (I want to create an Assault Duckie entity, but get a Smoke Effect entity.
If this causes the issue in the video, one solution would be to enforce mod load order to be dictated by the server. I was unable to reproduce this issue locally (in singleplayer), so it is only happening as a client. Note this issue might not be caused by mod load order at all, in which case please correct me.