That's weird, mine was opened up when I started the game right after the patch.
The jars in EX
Go straight east on the first junction, where Youmu meets the first 'snake'. The first jar is there.
Second, after Youmu drops way down, go to the far Southeast. The second jar is there.
Third, after crossing the two bridges, traverse through until Youmu meets two mushrooms on a lower ledge
drop further south, climb left, then go down at the junction. There is the third jar.
After the JUMP sign, climb up a step and try to jump on the gray area on the southwest. Go south on the first junction and get the fourth jar.
First checkpoint
After two 'Proceed Onward' messages and on the place where Youmu goes West through a narrow path, leap South and go east to find the fifth jar.
Second checkpoint
Go left through the gears. The sixth one is on the axis with the fast-spinning rod.
The seventh jar is on the gear right north.
Third checkpoint
Go south from the checkpoint then to the east
The eighth jar is on the pole with two platforms
Go through next place.
The final jar is on the far left side of the place with many frogs.
The one you most probably might have missed would be the fourth jar. Hidden very well.
And isn't there only 15 yellow jars in the main story?
I thought last stage doesn't have any yellow jars.
