First of all, thank you for the welcome
Now, about the project, no speed change at all, but I use different video sources like: Go Pro, iPhone and Drone (DJI Mavic Pro). U sually I set all my devices to work on same aspect ratio, frames per second an resolution. That's weird, as I said I don't understand why exporting only the video works and after only the audio also works, but both together that hang.
Welcome to the forum
You shouldn’t have the problems you describe, so let’s see if we can find out why you have
Are there speed changes in your project?
Are you using a mixture of clip types - sizes and bit rates?
And don’t worry about posting in the wrong section, I do it all the time
it’s not the end of the world