Problems setting up Sentiment

I’m seeing ‘Site Sentiment’ in my Admin Dashboard for the past 2-3 months, but no sentiment is being shown.

I even tried running the same as an Sql Query thru Data Explorer plugin and changed dates to approx 2 years, still only blank result.

When I try run a ‘BackFill Task’ it gave the following error:


I took screenshot of almost 50% of the top area.

As shown in the ‘just-above’ post of mine that Back-Filling is failing, can someone pls tell how many days/how many posts will it take for this ‘Sentiment Analysis’ to work or show something (i.e. wo backfill)?

I’ve searched ‘Back-Fill-Failing’ on meta, but no solution has been found anywhere.