ci<, etc. work but
ci' do nothing. The text inside the speech marks is not deleted and I am not put into insert mode.
I have a Dell laptop running Ubuntu OS with the standard British English key mapping.
edit: I think the problem may have been that I was trying to edit curly quotation marks aka smart quotes rather than regular quotation marks. The text I was practising on was copy&pasted from the internet whereas when I type the quotes for myself the commands do then work when I want to edit what's inside.