Undersized parties don't allow relic progress?

[Jetstream_Fox]

I did the last of my book dungeons solo/unsized, so I know for a fact you can do it~

It might have been bugged on my end, the only thing is I was switching between weapons during the run, but finished it with the relic on. Maybe when I get back home I'll run it again. So hopefully it was due to me switching around, though I remember when I finished my zeta I was able to switch from the relic to something else during the books and get credit as long as I had the relic equipped. Maybe this is what changed.