Also, I have checked the blocks included in blk00971.dat & I've noticed that the timestamps range from last week of August to Mid September 2017.
And blk00975.dat's blocks are from September 2017, one month after SegWit (BIP144) activation.

SegWit input/output scripts structure is a lot different than the regular transaction's.

That "parser" doesn't support and cannot read SegWit Txs.
Disclaimer: I could be wrong.