At the moment in Vault is hardcoded to use 256 chars as max path length.
By windows 10 there FINALLY! came an option to edit MAX_PATH (that was blocking path length all the time, default is set to 260=256 ;P), changing it in registry from 260 to probably any(?) could resolve my problem but I'm not sure about how it will work in Vault..
But if it is not realizable!
It would be good, if when creating a file path that is too long, a vault error message immediately appears (current number of characters, possible number of characters).