Thanks for taking the word screenshot literally, Daniel. ^_^
Well, since you've mentioned the other addons installed, can you run the UTX setup tools once and let them check their entries? They are pretty smart, so to speak, so they check their scenery entries and the terrain.cfg, which could be a source for the errors you are seeing. You will see the tool running through some sort of checklist, that's a good sign.
You could also start the FTX Central and switch the modes back and forth since this tool also checks if the terrain.cfg entries are in place. Maybe that clears you to see water again.
If not, you could post the contents of the terrain.cfg, which can be found in the main FSX folder. Will be a long post for sure but maybe some of the experts can see the error most likely defining some land mass where water should be.
Before any edits, make a backup of that file.