PDF preview using Windows EXplorer

An idea that would not fix this issue, but at least make it less of an issue would be if dropbox didn't download files just because they were previewed.  Because if I do open a file, and then save it, the preview works.  Again not a complete fix, but solves the issue 90% of the time.

It looks like this thread began back in Sept 2020 with no resolution. I have many computers using dropbox at work. Only one new computer has this issue exactly as described earlier in this thread. Once a file has previewed one time it can't be previewed a second time. I can look at files stored in OneDrive and .pdf files preview just fine. This issue makes my workflow tedious, I need a fix for this. Did anyone come up with a solution? 

Unfortunately no.

I have a terrible workaround. It works, but your not going to like it Nthreads .

If it's a folder i rarely access, I exit the folder. Select it and click online only, then go back in and have my 1 time previews.

If it's a folder with fles i absolutly need on my system at all times, or access regularly. So first set the folder to online only so it removes all files, then set it to local. If it downloads the file before you preview it, the preview will work repeatedily.

It only breaks when you preview a file that does not exist on your PC, and then you preview it. It will be forever broken until you make it online only or save it.  

@marcasi, thank you for the update. Hopefully, they will fix it soon!

Same!!! Help!!! 

I'm still having the same problem based on all of the feedback suggested ine conversation so far

As you can see I have the preview pane option on, but when I single click on the file, nothing shows up in the preview pane for PDF's and Excel files. Please help!!

This is a huge inconvenience for me as well.  I have a large number of work files for which it is necessary to use smart sync. After previewing once, the file syncs locally and is forevermore unable to be previewed.  ETA on a fix??

I have been grappling with this exact issue ever since I set up a new laptop and installed Dropbox.  Searched everywhere on the web, and this finally worked!  I hope this helps someone else.  The key to this is actually SIGING  OUT of Dropbox.  I did this by right clicking on the Dropbox icon in the taskbar, selecting the circle with my initials at the top right, clicking on "preferences", then selecting the "account" option at the top.  Then you will see the little box that says "sign out" next to your account name.  Then I uninstalled Dropbox and reinstalled it, and signed in during the setup process.  BTW, I have everything now set to download locally.  I don't know if that makes a difference, but it worked!  Good luck.

I have the same problem on Windows 10 using SmartSync.
I have a lot of big PDFs stored in my DropBox.
As long as the PDFs are in the cloud (grey round icon with the white cloud) I can see PDF previews.
When I open a PDF file, it get's downloaded, and it just shows the Adobe Reader Icon. No more Preview.
So after opening a file it gets downloaded on my computer (green round icon with white chechmark.)
In Adobe Reader I activated the option for PDF previews in Windows Explorer.

This works for files that are not in my Dropbox.
This bug is really annoying, because I need to browse a lot of folders with huge PDF files
Opening them to see their content takes very long.
It would be nice if Dropbox could preview .tif image files.