I have a script that generates a battery health html file using Windows powercfg report.
The html files uploads successfully to the asset page, but I can’t view (download) it.
It just launches a new tab and takes me back to the same asset page.
Is this a bug or is syncro blocking the launch of an html file in the attachment section ?
I wish I had an answer for you, however, just here to say that this has been an issue from day one for me, as well. Attaching a link to an asset has never worked for me. Wish it did because it would be very useful.
Hopefully someone from Sycro can jump in here, but it seems like your post is 11 days old and no one has, so there’s not much hope from this end. I was considering submitting a support ticket but it was never that critical. Maybe I will now.
We had the same experience with html. We just converted our reports to formatted text. Some have suggested changing the extension to .htm. Maybe even try.txt or an unused like .shb (Syncro has Bugs) 
extension and associate that extension with your favorite HTML viewer.