Interestingly I'm having a very similar issue. I did upgrade to 2.3.1 around the same time the problem started it looks like. I didn't notice it until today I opened Plex but it appears Tablo Ripper hasn't been processing new recordings automatically overnight for the last several days.
I had a problem long ago where the log showed the service didn't have rights to my NAS so after we worked on that and got it figured now after every install I go into the Service and specify the necessary credentials and that has always worked. That also wouldn't seem the problem now because the log doesn't show that rights related error at all.
I tested by recording a random show this morning and configuring Tablo Ripper to run at a time starting a couple of hours after that show stopped recording. The show does NOT show up when I click New? even though when I right-click the show the only option is Mark as 'NOT new'? implying it thinks it's already flagged as New.
So it's almost like it's not actually seeing it as new when scanning to determine what to process.
I'll PM you the relevant portion of the log. It looks like it logged the show as new according to the flags, it just didn't process it.