UPDATE
@Hardcawcanary Thank you so so much for your excellent advise. Your step-by-step instructions solved the problem of the Memory Calculation problem. I am so thankful, and grateful. You’re a livesaver.
For anyone else struggling, the step-by-step instructions by @Hardcawcanary works when you are struggling with the Memory Calculation stuck at 0% or so.
Additionally, everytime you make changes in the game, unfortunately, it seems you have to rebuild the HLODs. After the first successful memory calculations, I noticed some bugs in the game, fixed those, and then the memory calculation didn’t want to work again on launch. So I again rebuild all the HLOD exactly the same way @Hardcawcanary explains above, and then the memory calculation works agait.