For someone saying they're tired of people being flippant, you sure know how to embody what you apparently hate. In troubleshooting, you typically ask questions for more information and provide information in return to try to isolate a problem. It is very common that someone who says saves don't work hasn't played for the last several updates. How am I supposed to know how recently they played the game? If someone is using a save over 9 months old, it's extremely possible something might have broken in the mean time.
How is what I asked "vague"? I was actually specifically trying to rule out what might be causing the problem. And what do you mean by "on both sides"? I'm not on anyone's "side" about anything. I was trying to find out what might be wrong.
I also never saw mention that they were using a compressed version this time and uncompressed previously. Just because you might have guessed correctly doesn't mean this is automatically the problem, either. It might be the issue, but it could also be something else. Did you even ask for any information to learn whether what you suggested even applies? I actually hope that uncompressed-to-compressed is their issue so that it works for them now. But the aggressiveness of your response was completely unwarranted. I'm sorry your day apparently is going badly for you.
Also, if my saves worked and their didn't, it's possible providing a save file would let them continue anyway; maybe I was suggesting that if we didn't figure out their issue they might be able to use a save that worked for me. But that's not helpful? Sure, if you only say that to be a douche; that's not what I was doing.
Seems you read my post whilst projecting meanings that were not there. If you read it again after a day or two you will find all the answers to your questions.
Note I do not know if the possibility I mentioned is the main culprit. It was only an illustration of what one explanation might be and showing that talking about version numbers only wasn't sufficient for a broad understanding of the problems at hand.
I have been interested in the whole topic though, in particular as when you've been around for a while, you do read widely different opinions and experiences about what causes games and/or saves to "break". And so I have done some (limited) experiences where I would download more than one packaging of a game across multiple releases and test the portability of the saves. Doing it that way allows me to control all parameters of the tests, whilst also ensuring I know all the tiny potentially important piece of information that may be causes of issues.
I do not have conclusive results, and have a sneaky suspicion a lot may be down to devs (that includes modders and compressors) needing to pay more attention to details at time, whilst its the game engine on others. But the general gist to minimise issues (probably need to specify, this will minimise issues only, not completely remove them), remains to use the official, unmodded, releases only. As unfortunate as it may be to accept.