I'm not sure why you are seeing this all of a sudden but you should be able to fix it quite easily.
Locate the block in Pulse and select all of the text and cut it to the clipboard. Select the source code view (<> icon) and paste the code you copied into there. Click on the source code view (<>) icon again and you can start editing the text you want to appear in the block.
At the moment Pulse seems to think you want to show the source code for that block as I can see all of the code is encoded which the process above should undo for you.
All the best,