SSMS debugger should show the contents of TSQL table variables
Inability to see the contents of TSQL table-valued parameters or local table variables within the Auto/Local pane seriously impedes the ability to debug TSQL code that depends on them.
There are workarounds, for example this one...
...but they are tedious and tend to "eject" the developer from the current "mind-frame" exactly at the moment this ejection is most harmful - when trying to understand a complex bug.
Please use Debugging feature in SSDT. TSQL Debugging has been deprecated for now.