I don’t know if this a bug in Renoise, Kontakt or just how Windows 11 behaves, but sometimes when I open an old song file (with missing Kontakt instruments, or anything that leads to an error popup), and go to another program (web browser etc.) while waiting for the song to load, the loading gets stuck to a missing instrument, and if I select Renoise, there is no popup on top of it, it’s just stuck at “Loading song… ‘blabla.xrns’ (Document)…” and never gets anywhere because it’s waiting for input.
So, changing between Renoise and another program, you won’t have any kind of popup to click on to get forward in the loading, however, if you go to the other program, and instead switching to Renoise, you minimize it, either by clicking on its icon on the taskbar or top right minimize button, suddenly there’s an error popup on top of Renoise that lets you fix the missing contents issue and get forward with loading.