Reproduction steps:
1. Create a new Unity project.
2. Enable Unity Services (Window > General > Services).
3. Build and open an Xcode iOS build.
- Make sure "Build Phases > Process symbols" phase exists (screenshot1.png).
4. Build it to iOS (you may want to delete the log file from step 5 before build to clear it as it contains older logs).
5. Open "symbol_upload.log" file, which should be located in the "Library/Logs/Unity" folder.

Actual behavior:
...
time=“2019-01-08T19:33:36+02:00” level=info msg=“Found 0 files to check, scanning for binary images now...”
time=“2019-01-08T19:33:36+02:00” level=info msg=“Found 0 binary images to process (not all files contain a binary image, and some contain multiple images)”
time=“2019-01-08T19:33:36+02:00” level=info msg=“All 0 uploads completed with out error.”
...

6. Repeat steps 4-5.

Expected behavior:
...
time=“2019-01-08T19:34:07+02:00” level=info msg=“Found 2 files to check, scanning for binary images now...”
time=“2019-01-08T19:34:07+02:00” level=info msg=“Found 1 binary images to process (not all files contain a binary image, and some contain multiple images)”
time=“2019-01-08T19:34:07+02:00” level=info msg=“Log for folder Contents:
...

Reproduced with:
Xcode 10.1
2017.4.18f1, 2019.1.0a13