When the game is re-loaded, the blocks and items of the mod are registered randomly. This causes mods that save data using registry position rather than name (such as flashback) to become completely corrupted once the game is restarted.
Tested on 1.1.9+1.21.10, on 1.21.11; with only FAPI, Flashback and ClutterNoMore installed.
When loading the Flashback file without closing the game:

When loading the Flashback file after closing the game:

When the game is re-loaded, the blocks and items of the mod are registered randomly. This causes mods that save data using registry position rather than name (such as flashback) to become completely corrupted once the game is restarted.
Tested on 1.1.9+1.21.10, on 1.21.11; with only FAPI, Flashback and ClutterNoMore installed.
When loading the Flashback file without closing the game:

When loading the Flashback file after closing the game:
