Publicize: stopped posting to twitter

I have a daily scheduled post and for the last 2 days neither post has been posted to twitter – but they have been posted to facebook. I’ve checked my audit log and no plugins have been installed/enabled/upgraded since 15th Nov and Jetpack has posted to twitter since then, just not the last 2 days.

First question, how do I start investigating why not? Second question, does Jetpack write an activity/error log and if so how do I access it?

https://www.ads-software.com/plugins/jetpack/