That’s the worst, and it happens surprisingly often. The trouble is, Committees need people on them, so roles have to be filled by hook or by crook. The further down the voting order you go, the more likely it is that unwanted roles will be filled by someone who was unsuccessful earlier on, as a kind of consolation prize.
I really strongly feel this way of populating Committees needs to be improved on. I’m not sure that there’s a system fix (although now I’m wondering if it would have been sensible to completely separate Principal Committee elections and other Committee elections, in the same way as P&R and Committee elections are separated). Instead, I think it relies on Deputies being willing to put themselves forward for unenjoyable roles from the outset (maybe you choose one role out of enthusiasm, and a second out of duty?), and also on coordinating with others so you know where the gaps are likely to be, and you’re prepared to put yourself forward to fill it.
No one person can do the work of the whole States. You are not obliged or expected to step forward whenever there’s an empty role. What you can do, though, is work with others beforehand to make sure there’s a core of competent people prepared to stand for each Committee, to minimise the risks that go with unwanted roles.