Removing the whole lines about starterContent in the .ini worked, no need to delete the StarterContent itself
[StartupActions]
bAddPacks=true
InsertPack=(PackSource=“StarterContent.upack”,PackName=“StarterContent”)
It also fixed another annoying issue about a starter content material I was using and which keep giving warning message because of usage with NaniteUsage being set to false (while it was actually true in the material…)
Thanks.