I remember facing the boost::filesystem::space: Operation not permitted issue once as well. I had to recreate a new folder in the same disk and copied my blockchain data into it and reattempted the synchronization. It worked fine after that. I'm not a 100% sure if this would help solve your problem but might be worth the try. Also make sure that no other application is placing any form of locks on this directory.
If not, from your bitcoin.conf I figured this was set as your datadir "datadir=/media/ancientevil/Storage/BitcoinBlocks" and if this is your HDD with 750 GB if free disk space then it could probably mean a corrupted db when you tried to stop reindex?
Also from
https://theboostcpplibraries.com/boost.filesystem-files-and-directories "boost::filesystem::space() retrieves the total and remaining disk space". This is something used to calculate or get the used and available disk space.
Thanks for the reply. Ive been trying for days to fix this. I still have no idea what to do. I am totally surprised how little there is in terms of dev support. I am reformatting my storage drive and removed bitcoin core entirely. I am going to try to reinstall once more and if that fails im off to ethereum. I am wondering if I am wasting my time even trying again with bitcoin. The total lack of help is kind of stunning... Maybe if my question was related to the price