I just tested your posted files, and had the same as you had: not being able to save the Gcode file (as I now understand you meant with the second pass). I had to save it with a edited (shortened) file name, and then it went ok.
Now I understood your problem: I have it had several times with different Beta's as well, but with me it didn't seem that the length of the filename was the issue, it just had to be slightly different than the 'standard' generated Gcode. But I can be wrong.
It surely can get some improvement; I know that there was a fix in the past already to shorten the filename when there are many different stl's are placed on the build plate.
Let's ask Jonathan nicely to think about it, as for new users this is frustrating.