How to pass through Alt + Shift + [number] keypresses to OS

I have set my Windows to switch keyboard layouts using the Left Alt + Shift + [number] key combinations. The switching works everywhere except in LibreOffice, it seems that LibO internally defines Alt + Shift + 1 etc. as its shortcuts and won’t pass them to the OS. Is there a way to make these OS shortcuts work in LibO? Is it a bug that I should report?