Report Builder - Display selected parameters on report page

I know that this thread is old but I finally solved the issue.
=Parameters!YourParameterNameHere.Value(0)
Use that for if you only expect 1 value to be returned.

For the potential of multiple values being selected use
=Join(Parameters!YourParameterNameHere.Value,”, ”)
using .Label instead of .Value can result in awkward spacing between selected variables. You can test it out with your data.

The reason why this happens is because Parameters are Arrays. So if you want a particular value from the array then you need the .Value(value position). For the Join it will work through the entire array so you don't want to limit it to a particular value. Note that Arrays start at 0 not 1.