How do I hide the Poll option from the question section? (I have found a previous post on similar topic but the provided CSS no longer works - in fact it causes more issues)

Try using this CSS to hide the Poll checkbox:

#ask-inline-form > div > div:nth-child(1) > div > div.ui.horizontal.middle.aligned.list > div:nth-child(1){
	display: none !important;
}

This code assumes the Poll option is the number one option. Usually, right below the profile photo in the Question box. So add this CSS to your Tribe, see if that works.