Hi! This appears to be fixed in linux-image-5.14.0-3-amd64 (5.14.12-1) -- I had downgraded the kernel back to stable (5.10) until now; now I just upgraded back to the latest kernel image (though I upgraded the full system, so possibly the issue was somewhere else rather than the kernel) and hibernate is now working as expected! So I think the issue can be closed. Thanks! Dov