The main problem with Safari right now is Apple just released Safari 11.1 which has a severe bug that breaks Construct 3. We've filed a report with Apple who are working on it: https://bugs.webkit.org/show_bug.cgi?id=184502
We're doing our best to patch Construct 3 to avoid the issue in Safari. The latest r95 includes a workaround, but it may take some time to get right, since an essential feature is simply non-functional in Safari 11.1. I must point out that it is Safari that is broken, not Construct 3. Despite that we are working hard to get Construct 3 back to normal in Safari. It's quite frustrating for us since Apple are a multi-billion dollar corporation with thousands of engineers, and their software is broken; we have three developers (one of whom is currently off sick), and Apple's mistake here has left us in a spot of bother. I apologise for the inconvenience, but we are actively trying to sort things out.
For the time being I'd recommend using Chrome on a desktop system where everything should be working smoothly.