I have a Calendar one of my websites (https://www.bstai.ie) which was working fine, but now when I click on the event, it does not display correctly and basically does not work. I am using Events Calendar and thought that perhaps it was that, so I contacted their support but they couldn’t see anything. I contacted my hosting company and they suggested disabling plugins, etc. I did all this and nothing fixed it. The events can be added fine, show up on the News page and Calendar fine, but when clicked upon, they show a strange summary text version of the page which doesn’t function.
Eventually I went to where I have kept the draft (http://www.herrflynn.com/wordpress) went through everything again (disabled all plugins, deleting some even) and no success. Being a bit inexperienced, I was very afraid to go back to the basic Twenty Seventeen theme, but had to try and see what would happen. The Calendar worked fine, displaying the individual event pages fine again.
So it looks like it is the Sydney Pro Theme - that is the only thing I can conclude.
Any help solving the issue would be greatly appreciated. The group (bstai.ie) are delighted with their lovely, new, fresh, modern website, so I want to try to have the events displaying properly as soon as possible (they have a conference coming up too and will be using Eventbrite very soon for their tickets, hence the urgency to get everything fixed).
Thank you in advance.
Screenshots of same event in Twenty Seventeen (correct) and Sydney: