All sorts of "aminals" will take a shine to a few tender shoots. I use a "cloche-shaped" piece of stiff plastic netting (lightweight fencing material) over a lot of stuff, mostly as an insurance rather than as a specific deterrant, but have "lost" whole rows of seedlings when I didn't have enough netting to go around, with and without any traces of slug/snail presence, so I'd blame birds or rodents if there's no trace of anything else ... I can't see woodlice being a problem , but maybe yours are bigger than mine

I do know a couple of neighbourhood cats with a taste for onions, believe it or not. I've only ever caught them nibbling the end of mature leaves, but I imagine they'd make short work of a row of seedlings if they fancied them !