Can't edit cost basis for some linked portfolios

Hi! For some linked portfolios that have holdings without ticker symbols (e.g., my corporate Vanguard 401k) I need to be able to manually edit the cost basis.

I was able to do this manually the last time I tried around a month ago, but it's no longer letting me do that -- in other words, there's no ability to go to Holdings and click in the Shares column to edit.

Any advice?

Thanks,

Marv