Did you also check that this folder is really the one used in env? There should be a line POOL_NAME="GNP1" there. (Assuming that you are using CNTools, since Coincashew doesn’t have those /priv/pool/ subfolders.)
You have made the impression that you really checked everything. So, really, really bad luck is the only explanation left. But that’s easy to say, since it’s not my own pool.
There was another thread here lately with pools with bad luck:
But, from those MOTO by @Judofish and AZ5 by @dvekris had blocks in the meantime: https://adapools.org/pool/d5e493b834ee233104cff9d141ffae2d8d76a563f829e78987540046 and https://adapools.org/pool/11049c12ebde61e94531eb2d022b44ba4fdbc48eea14bf6cbf2a6f44
PLBPL by @nanap also has an ongoing stream of bad luck: https://adapools.org/pool/51120922fb9d7c0ecbb20378950da7880cb6dd9d3c9e06e17bff6aca Not as long as yours, though.
If there is a problem with your pool, it is very rare and well-hidden.
They don’t usually read the forum that intensively.