PS: I have now re-read your post. And frankly speaking, I don’t understand. Have you rebuilt the game using the z5 file with the Ozmoo builder? So you made your own disk where REU is enabled? Could you be more precise so I can understand what you did? If this issue is related to Ozmoo, I need to involve Fredrik and Johan. But I need them to be able to reproduce the issue.
Please also enclose if you’re playing this on real hardware with a real REU cartridge or what the environment is that you play the C64 version in.
One more thing to mention: if you rebuilt the disk using the Z5 file e.g with the Ozmoo Online builder, we are not talking about an issue of the game and your post here is at the wrong place. The disks I distribute here have REU disabled but work just fine. In such a case the way would be filing a bug report with the Ozmoo team. I forwarded Fredrik this thread, so he might give advice on that!