MNCTER

I had same issue today (I didn't had it before) I fixed that with logging out from my account and then logging back and then clicked try again. If still no work re-open launcher but if still no work I don't know what to do.

Mojang made it. Its says its modded version because you can't find it from launcher yet. So Its made by mojang but its not "Ingame" snaphot. You have downloaded it from mojang's website so its not snaphot in launcher. All downloaded minecraft versions from websites (not versions that you can find in launcher) is modded or game decide its modded. Thats why it says its modded version.