I’d prefer that Jim weigh in here (@BLUEFROG), but to me that sounds as if you need to clean the sync store and re-upload it. If there is no data on your iPad DTTG which hasn’t been synced to your Mac, I think I would simply delete the database on the iPad and sync it back; if the problem then persists, I would clean the sync store and then again sync the database back to the iPad.
However, Jim may have a more surgical solution.
I don’t see where you responded about anything logged in DEVONthink’s Window > Log.
Please post a screen capture of DEVONthink’s Preferences > Sync with the sync location selected.
Also, go into DEVONthink To Go’s Settings > Sync: Locations, tap the sync location, and post a screen capture of the Databases list.
I tried it, unfortunately no improvement.
The last screenshot seems to indicate a missing location. Also, I’m wondering about the “volume not mounted” messages in the log. Did you store DT data on external hard disks or network volumes?
Yes, my data is stored on a network server. The log error is since the update to 3.8.3 see article Help: Irritating Log Message
Your Log window is showing the home and DT-1 volumes aren’t mounted.
I’m guessing one or the other is necessary in the situation. Please clarify.
PS: If you are putting your DEVONthink databases on an NAS, we don’t suggest this unless you are on a gigabit Ethernet connection.
It is mountend. I see the path in my finder
And you can access its content, too?
Yes i can on my iPhone it works best
Is there a particular reason you put the database(s) on a NAS (not recommended by DEVONthink with indeterminate consequences) and instead put on local device (computer, phone, etc) and rely on sync?
Use the NAS for webdav sync and zip backups but not for routine access might avoid the syncing issue you have.
It’s because I have limited memory on my ios devices. And it runs without problems between iPhone and Mac.
Ok. But, you are having problems as you post here at top and you are getting some advice here.
Given limited memory on iOS devices, do you really need so much data on the iOS devices?
I’m not sure whether there are cross purposes at play here:
Those are two different entities; the reason I ask is that keeping the database on the NAS may solve a storage problem on the Mac, but can’t solve a storage problem on an iOS device, on which you cannot determine where the database should be stored. DT and DTTG use a decentralised model: every device has its own local copy of the database.
Sync via NAS (using WebDAV) is supported, whilst keeping the (Mac’s local) database on the NAS should only be undertaken if the connection between NAS and Mac is hardwired (or very high speed, reliable Wi-Fi).
I agree that this may not be related to your original query. Assuming the iPhone and iPad are using the same sync store, the settings on both devices are identical, and both are syncing some files in each database (test that with a new file in each database’s inbox), then I would go ahead as I suggested further up.
I took a look at my setup. It looks like my 2 databases, Work and Personal, are stored locally on my Mac. The type of file is DEVONthink Database.
On my Nas a file with the type DEVONthink Sync Store is stored. I retrieve this file via WebDav on my iOS and Mac device.
Thanks, that makes sense 
Be aware that - as I said - each device has its own copy of the database, so both the iPhone and iPad also have a copy of each database.
Yes new files appear. Only one folder is missing files. There is a folder of about 100 files and there are synchronized on the ipad only a part.
Ok; I can’t tell you why that is happening. But I would try deactivating sync for that database on the iPad, deleting the database on the iPad and then reactivating sync for that database on the iPad. That should put the database back from the sync store. Be aware that in doing so you would lose any records which are exclusively available on the iPad. I’ve gone through this procedure in the past; it’s not very surgical, I admit - but it’s the only suggestion I have, and I’m not seeing any other suggestions here. If the problem isn’t solved that way, then I suspect you’ll have to clean the sync store.
On my iPhone or Mac I see the data completely.
Have you verified the files are actually present on the Mac or iPhone, i.e., selected the file and made sure the content is visible?
Try another folder. Create a new folder on the NAS and copy the pdf’s and repoint to that new folder.
