iPhone photos won't show up in Photos

Which system version is running on your Mac? If your iPhone is set to take photos in the new High Efficiency format, only a Mac with High Sierra can read and download the photos. You can change the settings on the iPhone to use a more compatible format, see:

Using HEIF or HEVC media on Apple devices - Apple Support

Another problem may be iCloud Photo Library.

When you use a USB connection, you can only transfer photos and videos, that are currently in the Camera Roll. This will exclude all photos, that have been synced to the iPhone with iTunes.

Also, you cannot download photos from iCloud Photo Library this way, only photos, that are saved locally on the iPhone. If iCloud Photos Library is enabled on your iPhone, and the "Optimize Storage" option is also enable, not all photos will be stored locally, only smaller, optimized thumbnails.To be able to download the currently optimized photos as well, tap them to view them enlarged.

You may be using iCloud Photo Library, without being aware of it. The upgrade to iOS 11 may have enabled it. Check the Settings > Your Name > iCloud > Photos. DIsable "Optimize Storage", if it is possible.

Hi curlofsmoke! As far as I know iOS 11.4.1 cannot be run on an iPhone 4s, which your profile shows, so which iPhone do you really have? In addition to all the very god and detailed advice léonie has given you just one other tip...make sure that when you connect your iPhone to your Mac that the phone is unlocked! If it´s locked and you open Photos nothing will show up. Sometimes there is a warning to unlock my phone, sometimes there isn´t. This could be a small bug, who knows! I am running iOS 11.4.1 on my iPhone X, macOS 10.13.6 on my new iMac with Photos 3.0...all up to date, but I still have to remember to unlock my phone first! I don't have Photos set to open automatically when my phone is connected, because I prefer it that way. Hope this helps you! Regards, Ian.

I too just started seeing this behavior. All of my software on all devices is updated to the latest.

File format isn't the issue - as NO photos or videos taken on my iPhone X appear when connected to my MacBook Pro with iPhoto running.

iTunes and my iPhone get along just fine. No issues with "trust".

But after rebooting my MacBook and relaunching both iTunes and iPhoto... and after waiting for almost 20 minutes - suddenly my photos do show in the import window...

Have you already run iTunes to be able to confirm on the iPhone to trust the Mac?

Does Image Capture see the photos on your iPhone?

Great.

Since the Mojave update I also have to wait quite a long time for my iPhone X photos to appear in the Import pane in Photos ir Image Capture.