Dropbox iPhone consistently does not see or upload all photos

For the last several years I have had consistent problems with the Dropbox camera upload feature on my iPhone 11 Pro Max running latest iOS and Dropbox app. My work flow is:
1. Take photos
2. Launch the dropbox app and wait for all photos to upload in the foreground
3. Go to folder on Windows 11, and move the files to the appropriate long term location within dropbox

My problem is that quite often the Dropbox app does not see all the photos - between 20% and 80% of photos from various time periods are visible in the Photos app but NOT in the Dropbox app. The workarounds are painful. iCloud removes the create/modify timestamp, manual copy to dropbox is time consuming.

Troubleshooting steps:
1. Confirm that "icloud optimization" is not enabled
2. Remove app, clear out Camera Uploads folder/reinstall app (which does force sign out/in, and dumps cache)
3. Confirm that Dropbox has read permissions to all photos
4. Confirm solid network connection. Of course, since half the photos upload, and half don't, this cannot be the issue. But I do have 80 down/20 up.
5. I always run the latest version of both iOS and Dropbox
6. I have Camera Uploads ON of course, source = Camera Roll.
7. Do NOT use Cell data to back up
8. Save HEIC photos as HEIC

9. Include videos

So last night I did the usual remove app/clear out camera uploads dropbox folder on website/reinstall app.
* I have 7,231 pictures on my phone. the Dropbox App/Personal settings shows 7,185 photos found in the Camera Roll. So that's the first issue.

* Then on the Photos tab only 909 photos are found to upload . That's the second issue.
* The app apparently uploaded the 909 photos - but when I went to dropbox.com to look at the folder, there were only 429 pictures in the folder. Relaunching the app shows 429 photos in the folder. That's the third issue.

I don't see any pattern to which photos are not visible in the Dropbox app, and which are not. Almost the entire month of September is missing but for one photo, but most of August is there.