I have recently started facing this issue on Dropbox where my camera uploads haven't been happening for a while. I landed onto this forum and searched a few solutions
1. Reinstall the app - worked, but then the issue appeared again right after I switched to another app and came back to dropbox to monitor my uploads. I cannot do this everytime dropbox has an issue
2. Tried to "Clear cache" - didn't resolve the issue
3. Turned off Camera Uploads and turned it back on. Didn't fix the issue
4. Restarting - didn't fix the issue
5. Tried to change from HEIC to JPG and vice versa - that didn't resolve the issue either
My recourse - I have just sat on my phone for 30 minutes and uploaded all remaining pictures via Solution #1 and now I'm hoping I'll get the answer answer because there doesn't seem to be any permanent fixes.