Tuple error conflict when adding Unity Reflect to existing project

Hello everyone.

We've been trying to import Unity Reflect into an ongoing project to take advantage of some of the tools provided. Unfortunately we get a chain of errors all relating to this Tuple element in the SunStudy script.

Library\PackageCache\com.unity.reflect@1.3.0-preview.104\Runtime\Sunstudy\Scripts\Runtime\SunStudy.cs(131,23): error CS8137: Cannot define a class or member that utilizes tuples because the compiler required type 'System.Runtime.CompilerServices.TupleElementNamesAttribute' cannot be found. Are you missing a reference?

We don't get this message when simply importing into a brand new project, so the error indicated (missing a reference) seems unlikely to lead us in a fruitful direction. More likely there's some other issue that's going unreported somehow.

Has anyone else seen this before? Any suggestions on how to resolve this?

Thanks,
-John