Can you try to rename it to .txt? It's basically a text file with multiple sections, public key, signature format (?), signature and an actual json only at the end.
Sometimes the solution is so easy

Thanks, I never expected those 2 programs to adjust the view based on the file extension.
This shows another inconsistency though: the PUBLIC KEY part uses normal looking line breaks, the BEGIN SIGNATURE uses Windows line breaks (EOL). This is highlighted in vi by adding
^M at the end of the lines.
Maybe it helps; I've opened with notepad++ under Windows and looked pretty good/understandable (not that I've checked anything else than recovering the session, which can be done with the link too).
Any idea how to verify the LoG? Depositing without verifying is what makes many people send their funds to a phishing site, and that's all the more reason why verifying the LoG should be as easy as possible.