Open source (GPL3) - am I missing something?

Question

Iron

The partners have sent the source codes of the project [for further development]. Some of the codes are there, some are missing, instead of them there is a postscript, in a literal translation into Russian: “some of the source codes are missing, because contains open source code that has been modified and cannot be distributed." Plus, further offer to download these codes yourself and change them in accordance with the attached descriptions. Am I missing something in open licenses or are they? Or will the distribution of these codes entail the imposition of any further obligations on them? Or are they just making a fool out of me? In general, I don’t understand in any way ...
PS Some nuance is that the codes are not on software, but on hardware, maybe there is some secret meaning in this.

Answer 1

The GPL allows you to modify the source codes for your own needs and not distribute the changes. If the modified code is distributed, then it must be distributed under the GPL. Apparently, the partners do not want to distribute the code under the GPL and, therefore, cannot distribute it at all.

Answer 2

By the way, here is another interesting point. If you do what they want: that is, download the GPL source code and modify it according to the instructions, then the result is covered by the GPL. This means that you have every right to transfer the source code not only to the customer, but also to anyone else, that is, to put it in the public domain. In certain situations, you may even be required to do so. And they can’t forbid you to do this (under the terms of the GPL). So their reinsurance with not giving you the source code is useless in any case.