Fixed my issue, and one i have found across a few sites, about exporting/importing creator made islands on UEFN to Fortnite.
It is in fact, the culprit “OneDrive” that hinders fluid progress across the two UEFN / Fortnite .
Move all your work to “C\\” and everything should run smooth again.
Thank you again everyone that helped.
Looking forward to showcasing my work soon.