Anime at the cinema

Wasn't that the one you said you were the only one with a ticket at the time you purchased it? If there were little ticket sales for it, they may have pulled it, especially if they needed the screen for a mainstream movie coming in. Although, I have gone to anime screenings with as few as 6 people in the audience.
I was surprised how full my screening was, probably around 70% full, showed up as almost fully booked online so a fair few didn't turn up.

Even Dragon Ball Super: Super Hero still has a fair few going to see it, I saw it again before Free and there was around 10 of us.
September 21st-22nd for Gundam: Cucuruz Doan's Island (subbed and dubbed) from Crunchyroll
Update to this: from here
UPDATE 9/9/22: Due to recent events, the screenings featured within the United Kingdom have been removed from this article. We will update the article with more information on the release when available.
Looks like they're going ahead as planned. Listing has popped up for my local Vue and the CR article has been updated to state the UK screenings have been readded.
Seems Wednesday will be the sub showings and Thursday is dub. Nowhere local so I'll be trekking out for a subbed showing.

Not a dub hater but the modern Gundam dubs often squeeze out the emotion you get from the Japanese cast.