on Windows 64x, using steam api version 1.60 (the last one). With the following snippet, the game crashs on the function GetSteamID

if (SteamAPI_InitEx(nullptr)) {
  if (SteamUser()) {
    printf("SteamUser() is valid.n");
    try {
      CSteamID steamID = SteamUser()->GetSteamID();
      printf("SteamID: %llun", steamID.ConvertToUint64());
    } catch (const std::exception &e) {
      printf("Exception occurred: %sn", e.what());
    }
  } else {
    printf("SteamUser() is nullptr.n");
  }
  SteamAPI_Shutdown();
} else {
  printf("Failed to initialize Steam API.n");
}

SteamUser() is NOT null, as I can see "SteamUser() is valid.n". It is a valid ptr.
No exception, just a crash on that function GetSteamID()
With gdb, we can see in which function it crashes, which is the next function call after GetSteamID()

Thread 1 "MainThrd" received signal SIGSEGV, Segmentation fault. 0x00007ffa5a3de225 in steamclient64!Steam_NotifyMissingInterface () from C:Program Files (x86)Steamsteamclient64.dll

pointing my own steam client dll. It is up to date though.

I also tried using SteamAPI_Init() and SteamAPI_InitFlat() to load the API but I got the same result.

On Linux everything works fine.