Views cells cannot be inserted into layouts when Toolset Blocks is active

Symptoms

If you have the Toolset Blocks plugin active and you try adding a Views cell to a layout,  you’ll see a “spinner bar” that never stops spinning. Also, the Views dialog doesn’t appear to allow you to insert your Views cell into the layout.

Workaround

You can switch to Toolset Views instead of using Toolset Blocks, OR enable the Show both the legacy and Blocks interface and let me choose which to use for each item I build option found on the Toolset → Settings page under the General tab’s Editing experience section.