Petition Style disappears on some post/pages only

I have created a petition and added it in a sidebar widget because I wasn’t keen on your own widget. Anyway, this petition displays perfectly on some pages but not on others. On the pages it doesn’t, it is just a block of text that has all the pop up information too. I have looked for differences in these pages to find out why this is happening but it appears to be completely random. Any advice?

https://www.ads-software.com/plugins/speakup-email-petitions/