This isn't quite really a bug with the game but more so with the data crystal.
I've experienced a few strange problems, when I try uploading my data crystal to the new game (both from directly from the Itch app and from the web application both updated to latest) the file doesn't seem to carry over anything unique about encounters.
Checking the data crystal information itself shows that the stats from the first game are indeed written, but it still won't transfer the information over. I can share what's written if needed but I won't do it publicly in case you want that tidbit of code to remain secret but it might be a typo error in the code or I'm missing something in GT. I've already completed GT once, so there is save files still present before I transferred but I've also tried with new games (still with the old files attached to the game just separate saves.
I've made sure I've overwritten the original Data crystal that comes with the files in that game.
I've checked to make sure that the code was the same on both data crystals on Cruel Serenade and GT and they're the exact same.
I'm going to try a few things with the code to see if it might actually be a coding typo but I haven't really seen anyone else come up with a similar problem.
If you need additional information or need to privately message me feel free to ask or contact me directly.
I'll try a few things and comment underneath my own post with what I've done if I find a way to work around it.
A few notes if it helps:
-CS is on v. 0.4.1
GT was done on first release version and most updated from itch, both versions are on different files but are identically the same.
-I haven't touched the code at all.
-Both games are on the same drive, however it's an external one, I know this is only usually an issue with larger games and usually relates to lag instead but computers and coding are very finicky so it might also be an issue with this.
-I also retried the instructions a few times as intended and changed a few things. (i.e where the file was located and data values)
Sorry if the post is too long but I wanted to be detailed in the hopes it would make the bug fix easier on your end.