A quick workaround would be to export the 0:05 clip in native format, and re-import it for the Twixtor treatment. Or maybe if the clip was on its own track? (just a guess- I only use Twixtor in Combustion)
I think the Sapphire plugins will run in Premiere as well. I use them frequently in Combustion. A bit pricey, but worth it — very fast, and very clean.