SSIS project keeps failing with COM error

On my SSIS project I keep getting a COM error when I open the project, and then everything runs incredibly slow. The message says this:

Uable to case COM object of type 'System.__ComObject' to interface type 'Microsoft.sqlServer.Dts.Pipeline.Wrapper.IDTSObject100' This operation failed because the QueryInterface call on the COM component for the interface with IID '{...}' failed due to the following error: The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THRED))

I've no idea where to even begin trying to track down how to fix that. The solutions I've seen all say to register dts.dll but that dll doesn't seem to exist in my SQL Server installation.

Windows 2012 R2
VS 2017 Enterprise 15.7.3
- SQL Server Integration Services designer - 14.0.3002.101
SQL Server 2016 Mgmt Studio - 13.0.16100.1
SQL Server 2016