If you ever want to know where any attribute is stored, after updating the DWH, go to the domain. If you edit the domain, then edit in designer and you can expand the tree to find your custom field . Click on it and the table name shows there. Depending on what you created.
Most Investment fields go to DWH_INV_INVESTMENT table in the DWH . Most likely, your custom field is in the DWH_INV_INVESTMENT table, as our custom project fields are in the DWH_INV_PROJECT table. Again, to be sure, find it in the domain. It is easy to find, as well as if you have ever changed labels and missed the object label (and only changed the view label), the DWH will pull in the object label and not the view label. It is here, in the domain, where you can edit that.
If you look at CA's Excel sheet that shows Advanced Reporting Domain Field Description, then it shows where all the OOTB fields go. You will see where the Investment object covers across several DWH_INV_*** tables.