I am having a similar issue reported by JohnLuke.
I start SSC after Elite is running, I have configured it properly as it does recognize that Elite is running, says correctly the system I am at the moment and once I take a screenshot it does convert it without any problems.
BUT, at the moment it starts working in the screenshot it "looses" reference to the current system and saves it with unknown in the system information. (I have removed part of the folder path manually)
Another thing, my commander name is not FID as it is recognizing and adding at the end of the file name (as per my configuration for the file name).
Here the full log since I click the START button (version 1.5.6):
1/23/2019 7:46:49 PM - Detected that Elite: Dangerous 64bit is running.
1/23/2019 7:46:49 PM - Ready to start
1/23/2019 7:46:52 PM - Watching for new images at ...\Steam\userdata\49123224\760\remote\359320\screenshots
1/23/2019 7:46:52 PM - Logfile: ...\Saved Games\Frontier Developments\Elite Dangerous\Journal.190123185336.01.log
1/23/2019 7:46:52 PM - System found: Gria Drye OS-F b17-6
1/23/2019 7:46:52 PM - Body found: Gria Drye CQ-J b15-12 5
1/23/2019 7:46:54 PM - Stopped watching for new files
1/23/2019 7:46:58 PM - Ready to start
1/23/2019 7:46:59 PM - Watching for new images at ...\Steam\userdata\49123224\760\remote\359320\screenshots
1/23/2019 7:46:59 PM - Logfile: ...Saved Games\Frontier Developments\Elite Dangerous\Journal.190123185336.01.log
1/23/2019 7:46:59 PM - System found: Gria Drye OS-F b17-6
1/23/2019 7:46:59 PM - Body found: Gria Drye CQ-J b15-12 5
1/23/2019 7:47:11 PM - Valid image created: ...\Steam\userdata\49123224\760\remote\359320\screenshots\20190123194711_1.jpg
1/23/2019 7:47:11 PM - Waiting for image to be closed.
1/23/2019 7:47:12 PM - Sourcimage: ...\Steam\userdata\49123224\760\remote\359320\screenshots\20190123194711_1.jpg size: 189.60 Kb
1/23/2019 7:47:12 PM - Journal file copy argument issue: Loop 1 Argument 'Start' must be greater than zero.
1/23/2019 7:47:14 PM<System not found>
1/23/2019 7:47:14 PM<Body not found>
1/23/2019 7:47:14 PM - Invalid character " found and removed
1/23/2019 7:47:14 PM - Last output image: ...\elite_dangerous_dw2_screenshots\unknown Gria_Drye_CQ-J_b15-12_5 2019 01 23 19 47 FID.png size: 1.22 Mb
Here the configuration I am using for the file name:
%s %b %f %g %Y %m %j %H %k %c
It does appear that there is some error when it tries to read the journal file and that probably cascades causing all other errors.
The log above is with EDDiscovery closed, I do use it often while exploring.
I realized I was using the Steam screenshot folder as well as using the Steam F12 to take screenshots.
I corrected the configuration to use the Elite Dangerous screenshot folder and also used F10 to take screenshots now I get most of the information correct in the file name, but the commander name continues to get the FID, which is an internet ED id as we can see in the log file, that needs to be corrected in the code.