I don't mean to sound demeaning, but have you ensured the film was loaded emulsion side toward the lens? Basic mistake we've all made. If loaded backwards, the antihalation coating on the backside would pretty much prevent an exposure.
Also as a ballpark guess on your process try much stronger developer concentration, just to see if anything comes up.
^that's a good one to rule out!
I just clued in to it being 11x14 film, so economics indicates a clear resolution.
If I can summarize...stop me if I'm wrong...an exposed and developed sheet shows fog (or uniform density) all over the sheet, but not on the edges which are masked by the film holder. The edges are clear film base. Is that correct? If so, then unwanted exposure occured in camera afte the darkslide was pulled. Check your bellows for a large gaping hole (okay, not likely), or maybe you didn't close the lens before pulling the dark slide? Sorry if that is insulting your intelligence, but it's definitely the most popular way to uniformly fog film.
If it was fog, it would be across the entire sheet, and the holder rails wouldn't be visible.
If I'm way off base, can you scan a corner of your film, something which shows the image you were exposing for and the fog?
The oldest i've gone is tri-x and plus-x pack film that expired in '78. One was partially exposed. Came out a bit thin but were printable. The packs that were unopened and stored in an air-conditioned room were outstanding.
Now that box of kodak 11x14 paper from the 70s/80s that had obviously been stored in a hot, damp warehouse for years (a shame, 250 sheets..) didn't fare nearly as well.
I miss pack film.