Navworks screwed the pooch. Plane and simple. They will either fix all the installed units or get their asses sued off. And if anyone installed using the FAA rebate, you now may have a fraud case against the government.
It was approved, however, Navworks changed the product for whatever reason. Anyone who has been in aviation more than a few weeks should now an approved product is essentially locked down from modification.
They tried to be slick and got caught. Hopefully, they make it right before the subpoenas start rolling in.
That's probably a bit much. Anyone who's built anything with modern electronic components has had a part number changed on them by vendors, usually because there was some tiny manufacturing change in the part so they couldn't call it the same part number, even when it did exactly the same thing. L
The issue in the certification world is that you need to source your parts from a vendor who'll keep stamping the same part number on the thing for you, or your certification suddenly goes moldy.
Dad dealt with this all the time in his career of selling millions and millions of electronic components.
A module like a GPS module will be worse. Even a firmware update to the module to fix a real honest to God bug in the thing will invalidate a certification unless appropriate paperwork games are played.
The real fun was when all the component makers began making lead-free versions of their parts under RoHS a couple decades ago. Every part number changed, even on stupid "jellybean" component crap like 5% resistors just so manufacturers could document for European authorities (at the time, now the world) that they're parts weren't made with lead or even had lead solder tinning on pins and leads. Fun times back then for everyone scrambling to do search and replace in Word for all of their engineering docs and resubmitting them all to various agencies who were all overwhelmed by the stupid paper shuffle.
There's a greater than zero chance this is all that has happened to Navworx. If they changed the GPS module, or had to substitute one that behaves identically to their original, they get to start over on paperwork. No real value is added by any of this, but it does highlight that as a manufacturer you have to be a total pain in the ass to your upstream distributors and vendors.
And if you're buying in low quantity, good luck having any leverage when the One Hung Lo plant in Shenzhen says they're changing the part number on resistor R27 on your board.