CM4 Mercury V2 Streamer with fresh install of Ubuntu 24.04, SO 1.4 and no activation. Tried Squeezelite V2, 1.6, played at least 2 tracks as quick test.
Some more testing suggestions. Are you able to put a fresh copy of Ubuntu 24.04 and SO 1.4 on X86 box? If not, then please detail how you upgraded your X86 box. Is the box dedicated to SO or there are other apps? Did you remove L(ogitech)MS 8.x before upgrading to L(yrion)MS 9?
Also, can you please enable LMS on your Pi4 and use Squeezelite on your Pi3.
My latest guess is that LMS is the issue here, rather than Squeezlite on Pi3.