I know there was 49k tickets sold last month. I expect about at most 55k. Which isn't that good considering she's Rihanna. She should have done Twickenham again, or Emirates Stadium.
She's Rihanna, and it's London.
She sold 96k tickets during DWT, and 175k during LOUD. I mean even LGOET was success, she sold 33k.
~50k is not bad, but it's not great either.
I understand Rihanna isn't about the whole go around the world and promote anymore which I don't really mind, but her team failed. The fact they didn't mention her tour, or even had a ad during her biggest performance in the UK since like 2012, was a mistake. They should have plastered the city with ads and commercials on TV/radio/social media.

If she doesn't want to promote personally than that's fine, but her team should make up for it with ads
Many people just assumed the show was soldout, or they didn't even know she was there.