Sensing Of block can show "backdrop # of sprite" in the blocks pallet

Expected Behavior

the sensing of block should only be able to show backdrop #s of the stage and costume #s of sprites.

Actual Behavior

In the blocks pallet, when the stage is selected in the right hand dropdown of the sensing "of" block you can set the left hand dropdown to backdrop #. Then, if you change the right hand dropdown to a sprite it does not update the left side dropdown.

Similarly, you can select a sprite in the right hand dropdown and then set the left hand dropdown to costume # and then switch the right hand menu to the stage. This shows "costume # of stage."

You can also get other mismatches like this, like x position of stage, etc.

You can then drag these incorrect blocks into the workspace.

It's worth mentioning that if you change the right side of that block while it's on the workspace the left side updates to an acceptable option immediately. That is the correct behavior.

Steps to Reproduce

Create a project
Add a second sprite to the project (doesn't matter how)
scroll the blocks pallet to the sensing category
Set the right side of the "_ of " block to the stage
set the left side of the " of " block to say "backdrop #
set the right side of the " of _" block to the other sprite
note: it doesn't update the block so it shows legitimate options
drag the block onto the workspace
note: it appears on the workspace

You can set these blocks in the workspace to a number of incorrect versions of the blocks

Operating System and Browser

Mac Chrome

Start with the sensing "of" block in the blocks palette and compare its dropdown behavior with the same block on the workspace. Reproduce the stage/sprite and backdrop/costume mismatches described above; done means the palette block only offers valid combinations and updates when the selected target changes.