Weird Issue ISOLDR and Tetris 4D ISO

[whschimmel]

Using the latest Dreamshell 4.0.3 on a Dreamcast with an G1-ATA Mod

I really love Tetris every now and then and my favourite Dreamcast version is Tetris 4D (JPN Release).

Long time a ago I downloaded a Dreamshell IDE ISO Pack which contained a Tetris_4D.iso

This game always worked fine in ISOLOADER.

I decided to upgrade most of the .ISO files to Full GDI versions and GDI Optimize them, most of these GDI's work but somehow I did not get the Tetris 4D GDI version to get past the splash screen.
The ISO I had worked fine so I decided to delete the GDI and go back to the ISO version.

Now when I launch the ISO in ISOLOADER I get an error on screen:
DS_ERROR: Can't open /isoldr/1ST_READ.BIN

Error also attached as Image

Removed any presets from ISOLOADER and even deleted my complete DS folder to get a fresh one from the GITHUB archive but still I get this error.

I know the ISO is fine, because when I open RetroDream 3.0.0 and launch the game from there it does work...

Does anyone know how to resolve the issue?