By the way I found the answer here:
For some reason this wallet keeps "forgetting" about the BNT, I have to keep adding it per the above link. A little frustrating, especially as it's consuming 186 GB on this laptop for a few BNT...
Neat, though, that when I search for "ethereum wallet how do i see bnt" this post is the second link to come up! The first, being the above URL, which is also neat. Anyway, I'm posting the above link so that when I come back here, I'll see that I've resolved it, even though I can no longer edit this post.