I'm not sure if anyone experiences this but whenever I'm not connected to the internet, YGOPRO crashes a short while after starting up.
It doesn't seem to crash after starting up while connected and then disconnecting after.

From what I can tell, YGOPro disables the updated card files while checking for an internet connection. As soon as it gets a connection (which is pretty much instantly), or it gives up trying (about 10-20 seconds on my end), these cards become useable again. This causes some decks to actually lose cards and not be valid to play, until the game realizes, that there is no internet connection.

Now, I was unable to create a crash using this on my end yet, but I would assume, that it could be related. Does your game crash while in a duel? Or just straight from the main screen? If it only crashes in the duel, I would advise to wait out those 10-20 seconds before starting your duel.

---

It crashes both in the main menu and in the duel.
If I wait for a short while anywhere on the menu, it crashes, though it seems to crash just starting ygopro up too.
If I quickly go to a dueling against ai, while dueling, it seems crashes randomly, but its always during the early game or even during the r-p-s.

I should probably try to play offline on a clean ygopro.