swimfix is probably swim broken
The idea for swimfix is intended for melee toons.
When the mob is above/below them they look up/down and swim in a circle until they match heights close enough to melee, so they aren't getting beat to death when directly below/above a mob, but not within melee range.
If you aren't meleeing, I'd just cut off swimfix. If swimfix is giving you issues you should turn it off on melee too. I never really got much feedback on it and that's why the toggle was added.
Depending on what body of water you're in, nav can be problematic as well. MQ2Nav is a 2d navigational mesh. Even under water it treats vertical slopes as walls, and so cannot path over them. It doesn't have a true concept of "Up" or "Down" because the mesh is attached to the ground. Which is why I don't run Levitation.
Automating water is a pita generally speaking. For example If your level of "wet" doesn't match a targets, then spells/abilities can't land on them. For example, if you're under water and they are not. Your feet are submerged is enough. If your feet are submerged but their head is submerged etc.