The fact that it's an isolated file suggests that it might be a corrupt file. This has been known to happen. In 7 years of using BIAB, it has happened to me twice.

Try opening the file and then, before doing anything else, save it with a new name. Exit BIAB.

Restart BIAB and try opening the new file and see if the problem persists.

If the above doesn't bring joy, start up Realband, open the MGU file, save it as an MGU file but with a different name. Close Realband. Now try opening the newly created file in BIAB.

Hope one of these approaches helps,
Noel

MY SONGS...
Audiophile BIAB 2025