Patchy output for topic modelling and n-grams

[ek00058]

Hello, I'm trying to extract graphs from the topic modelling tool but for some reason only the 'categorical' view works - the rest of the options just generate a blank axis. Ideally I'd like to see the output in 'stream' layout, but so far no luck despite switching machines and selecting different sizes of corpus.

This issue seems to be coinciding with the fact that 'top n-grams' is choosing to only display a drop-down list of terms and an empty axis. Everything else (phrase nets, word clouds...) is working fine - any thoughts on what could be going wrong?

[sdspieg]

How big is your corpus?