Spotlight not returning results for internal iMac drives - ".Spotlight-V100" folder has red forbidden sign

My iMac running [macOS High Sierra] has two SSD drives: 256GB with the OS on it and 2TB for data. Spotlight returns zero results when doing a search on both drives. Also other apps using Spotlight for searching (for example the Calendar app and Outlook 2016) return no results when doing a search. However, searching an external connected USB drive works perfectly, and also searching a shared remote network drive gives perfect search results! I ran these commands to trigger a reindex:

sudo mdutil -a -i off 
sudo rm -rf /.Spotlight-v100

and restarted the computer, but that didn't solve my problem: Looking in Finder, I see the root .Spotlight-V100 folder with a red "forbidden" sign. Is this normal? ***Log generated by a Spotlight Search Test in Mints :***