I have a few databases synced from my mac to my iOS devices. For many documents it works great and I can view them on, say, the iPad Pro well.
However too often (maybe 1 in 5 times) I only get the document icon with a download link underneath - sometimes I then can after tapping the download link see the document appear. But as said only sometimes, in, say, 1 out of 3 cases I cannot: After tapping the icon just stays. 
This happens for all sorts of docs: PDFs, Markdown, RTF… Indexed and contained documents… different databases… I have to say though, most of the time I did a search and then selected the document from the search results: Possibly this causes the trouble?
I have consulted with DEVONthinkK support, moved sync stores, re-downloaded databases, etc, but still this happens way too often.
Any tips how to set the whole thing up, that I can view the documents reliably in DTTG?
Whay kind of Sync is it - Dropbox, WebDAV, … ?
It’s not possible to troubleshoot the specific case without logs sent with a Support Ticket, but generally, the common reasons are…
- Files missing in the Mac database (ie. unhealthy databases)
- Indexing data but not Synchronizing content of indexed items. No contents in the Sync location means there’s nothing to download.
- Slow / unresponsive remote servers
With Box.com, it’s always possible you have triggered a Captcha. Per Box’s tech notes, log into app.box.com/ to respond to it.
Re 1: How to check for this on the mac?
Re 2: Since consulting with you I do set all databases to sync content.
Re 3: I experience this on pretty good broadband connections as well. If the problem is the box.com server I would at least expect some error message, but it just stays on the icon…
You would do a Tools > Verify & Repair on the database(s).
Also, check if the Sync icon in DTTG2’s bottom toolbar has a warning triangle on it.
Thanks Jim. Will do this when I’m back at my Mac.
The database is fine: Verify didn’t report an error.
I went back to DTTG and now (after quite a few seconds of starnge feedback-less unresponsiveness) the document opened. 