Voles maybe?

I'm not sure if this works but I read where someone planted garlic around their flower bed and it kept the moles and voles away from their bulbs. You can break up those broken bulbs and plant the scales 1 inch deep and they will grow new bulblets for the future but they would be a few years away from blooming. Also look around your garden for the open Tunnel of a mole. You can buy poison pellets to pour into that hole.

Moles are insectivores and do not eat plants.

Squirrels eat my bulbs, maybe yours do too.

If it's happening underground, with telltale tunnels, most likely voles.

I lost a whole bed of 35-40 lilies one winter to the little a-holes.

I have not tried this method but someone on this forum recommended planting garlic in a circle around a cluster of bulbs to deter those critters.

My species tulips seeded into patches of wild onions, weeds but they get a pass because that's where the tulips persist.

Do not pour poison pellets anywhere. You are poisoning everything when you do that. Find another way to deter or evict the critters because poisoning them will poison the entire food chain. Predators, like hawks, owls, foxes, and bobcats, eat the poisoned rodent (which can take days to die, by the way) and become poisoned themselves. There are better ways to protect your plants and home.

I had something eating my bulbs, so I dug them up and put metal screening wire around them, giving them some room to expand, and re-planted. I'll know next year if it worked.