Very slow first iPhone and iPad photo sync over usb-a with Catalina

Is your Photos library set to be the System Photos Library in Photos' General preference pane?

Post screenshots of what you're seeing.

I was just on a chat with Apple Support. The person advised: https://support.apple.com/de-de/HT204063 (NVRAM oder PRAM auf dem Mac zurücksetzen).

I don't think that is going to solve the issue

Okay, I ran a first sync after installing Catalina. It wrote the Photo Database in the iPod Photo Cache 5 hours and 10 minutes after I started the sync. All my photos were already on the iPhone XS, but Catalina might have wanted to do something new. I'll try another sync tonight to confirm that it is still broken (or if it works). Only time I can do without the phone for 5 hours is at night, and there is no time I can do without the iPad for 5 hours. Dealing with the photos is bad enough, but the only way to add an audiobook is with a sync. Spending 5 hours to add a new audiobook when you are done with one is a bummer.

That's great news! I've now tested the statement that albums directly under "My Albums" are remembered by the Finder and do sync and this works for me! So I'm moving the albums I want to sync to that location. That'll do until Apple fix the bug. :)

I have had the same problem as all of you since a random iTunes update months ago - I had to stop syncing my phone because the 16,000 photo s would take hours; Activity Monitor checking iTunes Open Files and Ports would show it accessing the photo directories very slowly. Upgrading to Catalina didn't help at all; the only difference is now the directories show in AMPDevicesAgent, which is 100% CPU during the entire sync.

On the very first sync from Catalina to my iPhone, Finder was 100% CPU and unresponsive except for the ex-iTunes-like labels on top (General, Music, Movies, etc.), and the cooling fans were running fast. After I force quit Finder after the first sync, any sync after that makes AMPDevicesAgent use 100% instead, but the calling fans don't need to spin up. (The first sync didn't copy everything and the copied images were not in time order; after the 2nd sync they all existed and in the same order.)

A worse issue is syncing to my iPad Pro 11". On that, it replaces about 30% of the photos with a solid blank image, and used space/free space shows it not using as much space as before. A second sync made no changes, but took even longer (I think 9 hours). I changed from All folders to Selected folders and just selected 1 to get rid of the rest (I'm syncing from a data folder that has about 50 folders inside it, so those 50 are what show in the Folders section), then went back to All; after an overnight sync, it was the same as before (and it looks like the same images that were blank before are blank now, but they're fine on my iPhone 11 Pro).

I think I've tried deleting the iPod Photo Cache in that data folder before (with iTunes on Mojave) and I din't remember it making any difference; but in iTunes it would show Copying 1 of 16,000 and show progress; Finder shows nothing (once it showed a completion percentage dial next to the iPad, but usually it just shows the sync spinning circle).

This problem has been going on for me for EIGHT MONTHS.... way before Catalina.

In fact, I even immediately remember the user "Squiddz" in this thread because he created another thread a while back. https://discussions.apple.com/thread/250270137?

To sum up quickly, I am not using Photo app. I have thousands of photos and videos on my computer in separate folders that I personally organized. I am syncing them to a 2017 iPad Pro. They are all in there now, but if I need to sync just one single picture again, that process has to literally take up the WHOLE NIGHT. It just has to read and scan everything all over again to just add one file. Before, a simple task like that took maybe 20 seconds or less.

It is beyond frustrating.

I, like others, have sent MANY notifications and requests to Apple to fix this problem.

but EIGHT MONTHS and even several updates later, the problem is still here.

Please Apple. This tiring issue really NEEDS to be fixed.

Yes, I deleted all pictures from my phone, deleted the ipod photo cache, and emptied the recycle bin. I synced about 30k pictures on several batches of about 5k each. The last batch sync took longer than the other cases, and when I checked, I got lots of duplicates. I can still sync more pictures in a reasonable time, but doing so can add more duplicates or even remove them. For instance, I added 5 pictures, but settings was showing I added 1,000 pictures, then I added 3 pictures and settings was showing I actually removed 1,500 pictures... this is very inconsistent...

I think it might be fixed - I had to sync a few months ago to add some songs to my phone and it took the normal amount; today after the macOS 10.15.4 update, I tried on a few devices, and it acted normal (I didn't actually add photos, but before just a regular sync would take a long time).

Same issues reported here:

https://discussions.apple.com/thread/250716707?page=1

Apple was not aware of it, but it seems proven now that it is a bug, so no work around will help :-(

At least many users reporting this bug, so hopefully Apple will work fast on solving it and publishing first Catalina update.

It is a bug in Catalina, so 13.1.3. does not result in any solution.

The really sad news: even the first Catalina update does not promise any help, and indeed does not result in any solution. So please continue to inform Apple about your issues. Not only here, call them, use contact forum,...