Thanks for providing your env info!
I see this info and you may be belongs to first point and second point would be a conflict since .net 3.5 upgrade is not planned?:
Resolution:
webMethods for Microsoft Package 7.1 supports only up-to .NET framework version 3.5 .
webMethods Package for Microsoft .NET version 9.0 supports latest .NET Frameworks 4.0 and 4.5.
HTH,
RMG
#webMethods#Integration-Server-and-ESB