We learn [Yumi]'s repeated this day for 1700 years, and her memory is patched over by the father machine. If memory and Investiture are so closely tied together, is the father machine also taking her Investiture? How does that work, because she's such a highly Invested individual, it seems like if it could take any Investiture from her, it would take all of it, like the nightmares did.
When I play with this, with tweaking memory and things like that, my go-to in the cosmere, in the three cases where you've seen it happen, is that those excising memories have to be really, really careful, or the body will reject what you're doing. So, all three times you've seen it happen, it's been one little sliver of memory is getting changed. The father machine might even just be overwriting it each day, basically blanking that Investiture, but not stealing any of it. Vasher does pull a little bit out when he takes the memory, and the same thing happens with Wit when it happened to him. But I think the father machine's doing it in a slightly different way, and it has to be really careful, or it'll be too obvious, and the whole illusion, the facade, will collapse.