iPhone videos and photos not uploading to Dropbox. Only some files upload, and the others don't.

Hi, 

My Dropbox seems to not want to upload Apple iPhone Photos and Videos to my created files. 

I create photo and video content which I need to distribute to clients using my iPhone however the upload process is almost non existent. 

I have the Essentials Plan with 3TB storage. 

I select the maximum files for upload (400 a mix of HEIC iPhone photos and videos shot in 4K 60FPS and mainly video files) and hit upload. The preparation process/loading bar that comes up before being able to upload the files takes almost an hour if not longer. Once this is completed, only some of the 400 files make it to be uploaded so many are missing. Then when I hit upload it says it estimates 2+ days. I do the same process because for one client they get roughly 1000 pieces of content, so need to upload more files. Same process again, it takes forever. 

My next problem is that the files then sit ‘waiting to be uploaded’ with maybe two or three with a loading bar next to them. They then do not load, and the estimated time to upload says 2 weeks. I might be lucky to get 3/100 files uploaded after 5 hours, but I do not know where the other 900 files have gone (they aren’t anywhere to be found and aren’t in the queue waiting to be uploaded) and none of the other files sitting there will upload.

I need this service to be efficient for my work so all the help or advice I can get to get this sorted would be appreciated. 

thank you.

Ash