I've been seeing a few lost Mavics and I know this will help.
If you use pretty much any DJI sUAV (in this case a Mavic) this is what you do find a lost bird.....it works every time.
First before you fly always update your maps for the areas your going to fly.
You'll need to zoom in to your map location at max magnification and make sure they become fully clear to see before you fly.

Now here's how you do it ..after you know that your DJI Drone is not doing it's own "return to home".
And you know it's lost for sure ... all you have to do is zoom in on your map box and were ever the red arrow is located,
take your phone or tablet with you and track it back to that exact location. It will be within 3 feet of were the arrow is located on your map.

If you didn't update your maps before you went flying update them before you go out searching.

Good Luck!

Good stuff but in case you didn't know there is a "find my drone " section in the app for drones that use DJIgo4. Older drones that can only use the djigo app don't have that option but that same advice saved me a while back.

not always the case if it disconnects from the phone

Good to know.