I have a number of user-scope modules installed in ~/Documents/WindowsPowerShell/Modules, which is in the PSModulePath by default. After installing via the windows installer, under user variables, my PSModulePath was set to ;C:\Users\justin\AppData\Local\Google\Cloud SDK\google-cloud-sdk\platform\PowerShell (note the leading ;, which looks like a failed attempt to append to the existing path), which caused the default path to not be searched, and my modules to all fail to import. This was a simple fix once I had figured out what was going on, but it took some time to discover.