Random freeze and BGM loss during battles in Valkyrie Profile

I’ve been having issues while playing Valkyrie Profile. This problem occurs randomly after some time of gameplay (usually after one hour or more) in different scenarios and situations. Therefore, there’s no consistent way to reproduce it — it only happens during normal gameplay from start to finish (the entire game must be played to observe the issue and I’m not sure if the developers are willing to test it that way). What happens: When entering or exiting a battle, there’s a brief freeze on the black loading screen, and the game loses its background music. You can still move around other parts of the dungeon and enter other battles, but it’s not possible to save the game or create save states. Sometimes it also happens after saving the game and opening the core menu on MiSTer to actually save to the memory card. In that situation, an icon appears in the corner indicating an open lid or read error, although most of the time the game continues normally afterward. When this issue occurs, the only option is to restart the game through the core menu. Because of this, I’ve lost a lot of progress and had to replay dungeons or parts of them. Despite that, I managed to finish the game completely. I’ve downloaded ISOs from two different sources, and the problem occurs on both discs. I’ve been playing since June of this year, and I’ve been using the most up-to-date core version from June and all subsequent ones up to now, using the update_all script. (Sorry, I don’t know the exact version numbers.) Thanks for your attention.