While changing or creating or changing Account object if we are setting the Password as anything non-numeric (like : 'Abcdefghijkl#' ) then it is failing but when we are sending one numeric alongside with it (like : 'Abcd1efghijkl#') then it is getting successfully implemented. We are using the BCrypt Hash algorithm. So is it mandatory for this algorithm to have a numeric value in the input text to convert it to hash? And when it is failing it is not showing any error in the console.
This sounds more like your project’s password policy.
Go to Security->Password Policy to check what the current policy is. I suspect you have Require Digit set to Yes.