Choosing default boot drive

I installed volumio yesterday and I encountered a minor, yet annoying issue. I keep Volumio on SD card in my Rpi4 and I have usb3 ssd drive with some music. The problem is, whenever I try to boot with the drive plugged in, Volumio refuses to boot. I have to disconnect the drive, boot, and only then connect the drive.

Apparently Volumio attempts to boot from the drive and fails, since the boot files are not there.
Is there any way to fix that? I guess I could just copy the boot files to the drive somehow (like I did with raspbian for example) but if there is a simpler way, I’d love to hear it.

usb3 ssd drive:
if your drive would be a logical, instead of a primairy active boot drive this should work.
so if you don’t want it to look for a boot drive don’t make any on the ssd.