Backup-SqlDatabase: Cannot bind parameter 'InputObject' Error Being Thrown
Please check
out my blog for a detailed explanation of the problem.
I was having the same issue, blogged after I couldn't find a lot of information online.  

The solution comes down to importing only the required module, in stead of the modules for several versions of SQL Server.

First check what modules are being loaded:

# Get loaded assemblies
([appdomain]::CurrentDomain.GetAssemblies() | where {$_.FullName -like "*smo*"}).Location




Next make sure your session is closed if you already loaded the modules, then use this modified script to load only the modules you need:

$TempArray = @()
$TempArray = $env:PSModulePath -split ';'
# 110 for SQL 2012, 120 for SQL 2014, 130 for SQL 2016
$env:PSModulePath = ($TempArray -notmatch '110') -join ';'  


Now, load SQLPS module and run commands.