Why do I get a notification that my iPhone is locked when plugging it in to sync files and photos?

Hey! So I have been having this issue as well for a long time, and some of the other threads (such as this: https://www.dropboxforum.com/t5/Mobile/iphone-5-unlocked-but-dropbox-says-device-is-locked-and-cannot/td-p/16791/page/2) have simply not helped.

This issue seems related to another one that has shown up a lot on Apple forums: The iPhone's internal storage/DCIM folder appears to be empty when plugging in the iPhone.

Here are my steps to get it to work, but this feels like a workaround because you have to sit and wait occasionally. Something seems wrong with the iPhone drivers or something. 

----

Before starting:

• Make sure iTunes is installed.
• Make sure Dropbox is working on your PC.
• Make sure AutoPlay settings are set to "Ask Me every time" for your iPhone. (In Windows 10, press the windows key, type "AutoPlay." In the AutoPlay settings, find your iPhone and make sure it is set to "Ask me every time.

------

Steps:

1. Open iTunes (not 100% sure if this is necessary).
2. Open Windows Explorer, and navigate to "This PC."
3. Plug your iPhone in (locked/unlocked, doesn't matter yet).
4. You'll notice in Windows Explorer, your iPhone should show up.** Double click on it. It will likely show an empty folder. 
5. The Autoplay notification should pop up on your computer by now, asking you what you would like to do with your plugged in iPhone. Click on it, and when the option to import via Dropbox shows up, DON'T TOUCH ANYTHING on your computer yet. If you click something and the Autoplay options disappear, you will need to unplug your iPhone and start again from Step #1.
6. If your iPhone isn't already unlocked, unlock it.
7. Now keep staring at the iPhone folder in Windows Explorer. Remember how it was empty? Well keep waiting (it takes mine up to 2 minutes after plugging my phone in), and eventually an "Internal Storage" folder should suddenly appear. This means that your PC has access to all of your iPhone content now.
8. Now click the "Import via Dropbox" button at the top right of your screen. 

Your photos/videos should now start importing, and you should NOT get the "device locked" message. One thing that is unclear to me is if your phone has to remain unlocked during the entire import process. I don't believe it has to be, but you'll have to see for yourself.

Unfortunately, you will have to repeat steps 1-8 every time you want to import your photos. 

I don't understand why it takes the iPhone up to 2 minutes for the PC to recognize its folders. This seems to be the crux of the issue. Can anyone shed any light as to why this is happening?

Please let me know if these steps worked for you, and if you need any clarification.

--

**This is the problem. When the iPhone shows up in Windows Explorer, if you double click it immediately, it will show up as empty. Normally, double clicking your iPhone in Windows Explorer should show an "Internal Storage" folder, and inside it should be a "DCIM" folder. For some reason, it takes up to 2 minutes after plugging in the iPhone for these folders to appear. Dropbox can only import files when these folders are working properly.