I'll give you my two cents on how I would run your Safari since your new to Minlab. I went through the same thing two years ago. First thing is you have a different beast in your hands and you will have to unlearn some habits you have from the AT Pro. The Safari has a new language you have to learn, just as learning a real language it will take time so don't throw away your machine or give up on it.
First and foremost you need to really slow down your sweep speed, the Safari is slow in reacting to what's under the coil. If there is anything being discriminated out along with a good target it will null out, go silent for about a second because of its slow reaction time to targets. So if your sweep speed is slow enough you might pick up the good target. In your post I'm going to guess you had the nail to close to the coin and your sweep speed was to fast and the Safari just nulled out. Get use to it that comes with owning the Safari, in the future you will learn to work around it and find what others have missed.
Now how to set up your Safari for the first couple hunts, discriminate out everything from 29 down to I think -10. With this setting you will find most American coins from Indians to $1 coins and most importantly all silver coins. You will miss all gold and nickels but you will not be digging every piece of trash out there. I hunt in ferrous sounds, I like it because coins always sound good to my ears in this mode. Check out my video on how, it's not the clearest and I need to redo it in the future.
https://youtu.be/-UmRcGGxMFM
If you want to find nickels undo 15 on the scale then dig the good tones that come up 15 not the broken sounds at that number.
When you get use to the sounds or language of the Safari start opening up more numbers on the scale. I have gotten use to running in all metal or at least having from 0 and up open, then you can hear everything and dig the good sounding targets. That will be months from now for you.
Most of all go slow, your there to find targets, not to cover as much ground as you can. Watch more of my videos and realize most of them are from parks that have been detected hard for the last 40 years but the Safari has found many good targets that were missed.
Hope this helps, remember take your time learning the Safari and you will be rewarded and come to love the machine....