Candy Soda Level 1968 must have a bug

I figured it out! When you go to make the 4th line of the candy stick at the bottom, make sure it's a fish with a vertical stripe candy. That will spread the purple jam into the blank 2nd column, and then you can complete. Just tried on mobile and on king.com and both worked.

I did exactly as you suggested twice and fish never went to jelly.