image is explanatory. Using and ipod running iOS13 I think the “More from [user]” thumbnails were blocking access to the “Taxon as good as it can be” checkbox. So I scrolled up a bit and clicked one of the thumbs up/down icons and it worked fine.
It wasn’t a problem on an iPad running iOS8, checked the box no problem.
small potatoes but there you go
(I’d upload a screenshot but it’s not immediately evident how to do that (I was expecting a prompt)