Something's not right with the sealing of the inner part of the Gaiter. Hard to say for sure looking at your photo.
Here's a section drawing, which hopefully shows how they should sit and be clipped

You will need to disassemble the joint to repair it.
A word of caution on the inner clip. Most replacement Gaiters come with (ordinary) Cable Ties. These are not a good idea to use. On the Inner, where you are having trouble, on the bigger angles that the CV can see in normal use, the head of the Cable Tie will often hit the Cage of the CV, causing them to break or become dislodged. On the Outer, because the tie pulls up through it's head at around 90 degrees (and not flat), that part of the Gaiter under the head, has no pressure on it and due to the action of doing the tie up in the first place, it tends to pucker at that point, leaving a gap from which they leak.
On the Inner part, I use Tie Wire as it ends up with a very small profile. On the outer, I use 'Flatie' Cable Ties or Stainless Steel Cable Ties, both of which pull up flat.