Here the condition:
ArcGIS Server, ArcGIS Portal, Editor - all 10.3.
Web App Builder 1.1.
All are on the same box.
I open an mxd and add some imagery files (SID files, about 50).
I publish mxd as a service, registering data source, fixing analyse problems etc.
The service works - I can display it in ArcMap, Portal and add to a WebMap.
But then, in a WAB app, the printing widget got stuck when I try to print this WebMap.
Browser debug doesn't reveal anything except print service timeout.
The imagery files are located in a folder with "everyone read/write permission".
Otherwise printing works OK.
If I open an mxd, add raster catalog from gdb and publish as a service - the widget will print.
The problem is only when mxd is made from imagery files.
Thanks in advance!