Today I wanted to deploy an multidimensional Analysis Services Solution to our test server, but Visual Studio crashed right after loading the Processing Task User Interface. The exception was: 'Could not load file or assembly sqlmgmt.dll Analysis Services Processing Task'.
One fix I stumbled across was to copy & paste files. If you are using Professional or Enterprise Edition you need to change the first path accordingly.
C:\Program Files (x86)\Microsoft VisualStudio\2017\Community\Common7\IDE\Extensions\Microsoft\SQLCommon\140
C:\Program Files (x86)\Common Files\microsoft shared\SQL Server Developer Tools\140
Restart your Visual Studio and you can redeploy your solution.