I have upload a remix where i use a sample from Admiral Bob. In the list of his uploads, the sample I used (TF Mellow Bongo Drums) doesn’t appear. I have noticed also that other uploads of AB don’t appear in that list, specially the first uploads of 2007 and 2008.
To attribute AB i have used the “I used or saw…” feature.

It is possible Admiral Bob hid or deleted the files so they no longer show up on the list.

Maybe the search at the ‘Submit a Remix’ page is limited to a certain number of results. Instead of searching for the artist you can search for the source title. Then the sample should be found.