I've been watching this error very often:
13:15:35: [-] 074/120 PHPBookmark url resolve failed
And in some other domains/platforms too. I think it's related with captchas not working on that sites.
However, the "bug" is that GSA SER is repeatedly trying to post to that sites, sometimes a few times each minute.
Don't know if it's a bug or I'm missing something, but it can degrade performance IMHO.