I sincerely apologize if this is, in any way, an inappropriate post here, but I'm too ignorant to find a better venue and I think this may help a number of people. I have recently been going round and round with the fact that a recent loot update(s) worked fine with Skyrim and Fallout 4 but kept failing to get the masterlist for Fallout New Vegas. The error message sent me down the dark trails of github address fails, fire walls, metadata handling, and eventually, head-banging.
Finally, looking at settings.toml, I noticed that every game listed showed : branch = "v0.10" except the entry for FalloutNV which said "v0.1.0". Changing this to v.10 resolved the error message for me.
Since this may be a typo affecting all users I just want to get the word out. If anyone has a suggestion as to where this observation would be better placed, please let me know.
Thanks all, especially wrinklyninja and the LOOT team!