Multiterm won't let me add new terms

Hello,

I'm having problems with termbases this morning: one (large) termbase in particular, so tried to open it in Multiterm to reorganise, but it wouldn't let me. Multiterm told me it needed to update (to 2017), which I allowed it to do, and then I was able to reorganise the termbase. However, having now added it back to my project, I get the message "Object reference not set to an instance of an object" when I try and add a term to any termbase - aagh! I can really do without this today, but would like to add terms on the fly - any ideas? I'm still using Trados Studio 2017 (because 2019 won't work with Dragon on my desktop). Would be very grateful for any solutions!

Many thanks,

Claire