BOM filtering is only available for named BOMs in EPDM.
After submitting the question i remember that...but i thought the filter was avail to the "Bill of materials" preview too. But i might be mistaken.
I don't like the "named BOMs". I have 6 different BOMs, and they all have names...lol. So i can only filter them once i save a *.BOM file inside the Vault. Saving the BOM as a *.BOM file, is what defines it as "named"....silly verbiage.