it saves files with the names but they are 0kb in size and cant be opened - if you have yours in 'list view' then check them and see if the open or of a proper size.
edit: ok ive re-checked and when expanded it either saves just the bit that you can see (not the whole thing) or it fails with 0kb files, I just done some now and the HLOG one has nothing in it - also ive noticed that sometimes the HLOG and QLN graphs save as 0kb files even when not 'expanded' and ive also had 1 SNR one save like that too...
see attachments, first one is the HLOG expanded ive just got by closing the program (save on exit) as you can see there is nothing in the graph, and the rest are the 0kb files (not expanded)
I've just checked again, and the graphs are saved properly when I click the "Take snapshot" button, or when I set them to autosave, whether they are expanded or not. What I haven't checked (yet) is whether they always save correctly when set to autosave on exit. It's possible that your problem only affects the Windows version (I develop on Linux) and that's something else I have to check.
When the graphs are in expanded form, the snapshots only include the visible portion. I could in principle make them include the whole thing, but it would actually be rather complicated, and in the case of VDSL2 it would result in rather large images. I could put this on the todo list, but I can't promise to get around to it very soon.
Concerning the HLog graph which you saved on exit, did you enable the HLog graph just for testing purposes and then exit immediately? If so, this would explain its lack of content - nothing appears on the graph until the next sample after it's been enabled. The same will apply to the QLN and SNR graphs.
..just to further add to my above post....
...does DSLstats use or modify anything to do with COM Surrogate or rpcrt4.dll ...?
I'm afraid I don't even understand the question. I use a cross-platform high-level development system (Lazarus), do all the development on a Linux 64-bit machine, then build it for the various platforms. I don't get involved in the low-level implementation details. The information is certainly available in the Lazarus source, but wouldn't begin to know where to look.