Agh, this. I've had a lot of mixed results with group conversations. Sometimes I luck out; it's a small enough group that I can keep track of everyone and get a chance to get a few words in, or there are a lot of people there with shared interests that I can talk with them about, or there are a good number of one-on-one opportunities, but most of the time it goes exactly like what you've all described.
I've been trying to work on building up 'scripts' to go through when meeting someone at an event, but it's still very much a work in progress, and I usually end up losing people after a few seconds of extremely awkward forced small talk.
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I'll just be over there by myself if you need me...