The below issues seem to have received no solutions so I wanted to raise them again as they are both affecting me to the point that progress is now stopped entirely. I was hoping that being able to reimport a heightmap tile level would be a work around for the main issue, which is, that when I import a tiled landscape only one heightmap/level is created in the level browser, and it is corrupted i.e. does not load and is never actually saved in the projects content files. I have tried every combination of settings in World Machine and the Unreal Engine import dialogue, I tried in version 4.19, 4.20, 4.21 and just reinstalled to v. 4.21.2 and still no luck. Hope someone can shed some light. Otherwise my short lived game dev days are over. Thanks.
Issue No 1 (main issue)
Issue No 2 (Unreals own documentation says that you can reimport hieghtmaps for selected tiles via the righ click context menu in the mini map, however I cannot find this option either)