It’s probably a problem with the source text you pasted in the block. To avoid this happening again, once you paste a text into the block, click on the “Clear Formatting” icon from the text controls. Then insert your line breaks, colors, etc. I tried it on the page you sent and rechecked after saving, the front end rendered the lines and in the Edit the line breaks were there as well:
Let me know if this works fine with you.