Dear Alexey,
with latest release, I retried orthorectifying with refine Seamlines options. It works now without setting the Fine level in Network options....
However it still does not give satisfying results with seam lines passing thru buildings (marked in red on screen shot).
Also, the OrthoMosaic was done on a small region (shown in model view).
However, the ortho shows an extent of 37928 by 25257 pix at 7cm/pix which does not correspond to the extent of region … It corresponds to full extent of model...
Attached is the log of processing. Note that
2018-10-14 07:58:31 Error: Connection closed (status code 0)
corresponds to attempt at sending Ortho task to Cloud processing after enabling it in Preferences....