If you can't spawn in using "day one" mod after 42.10 update came out, here's the explaination (from my comment under this mod:


So, the thing is that you have to set day length on 2 hours, exactly 2 hours now, since 42.10 patch.

Before 42.10, default day length was "1 hour".

So, my sandbox pre-set that I created BEFORE 42.10 had its day length set to "1 hour".
And that's EXACTLY why after 42.10, when default day length officially became 2 HOURS-LONG in sandbox settings, I couldn't create a save using my old sandbox pre-set that I've created BEFORE this small 42.10 change. I've had "1 hour" day length chosen in this sandbox mode pre-set, and I didn't notice this small change at first, but that's it.

TLDR: if you can't spawn in with this mod in B42.10 and beyond, then set your day length in sandbox settings EXACTLY on "2 hours"! It's now the default for B42.10 and beyond, so u gotta use it and not the old "1 hour" option!!!