But why then it is the same with OWB...?

I tested your suggested workaround:

Working:
https://github.com/AmigaPorts/ACE
https://github.com/jasonsbeer/ZoRAM-Amiga-2000-RAM

Not working:
https://github.com/amigadev/agaos (also not working with OWB)
https://github.com/arnaud-carre/LSPlayer (curiously enough it is working with OWB)