I'm posting this to try and help other people suffering the same issue.
My protected address stopped receiving emails from SpamGourmet a while back, I don't really know when, as I don't use SG regularly, and, anyway, the whole point is to stop spurious emails arriving! It definitely did used to work, though.
I tried to change the protected address to a different ISP but I'm not sure it did actually change, as you have to confirm the change, and I never received the email to do that.
I tried to post a request for help on the BBS, but you need to respond to the confirmation email to create an account - so no-go, also.
I tried creating a new SG account, but again, you have to confirm it, and I never received the email.
Based on other postings about simuilar issues, I checked spam filters on both the ISPs I tried - it was turned off. The SG emails weren't going into spam or trash folders.
On the ISP that provided the feature, SpamGourmet.com was whitelisted.
Emails to the disposable, SG email addresses were being received by SG, as I could see the counts changing. I could reset the counts successfully.
Soooo, what was wrong, and how did I get on this BBS?!
I resolved the issue by changing my protected address to a GMail one. That did receive emails from SG, so I was back in business.
So it would seem both the ISPs I tried block the SpamGourmet domain, but don't tell you that they are. It was even blocked when I disabled spam filtering. Rather sneaky. I'd better not name names! One is UK based, where I am, the other USA.