You did the right test. Don't leave the tape on too long! If it still leaks, maybe you have blocked front drains. This is not that rare. I have fixed quite a few cars with this problem. On a level surface, all 4 drains should drain onto the floor, but if the front end is downhill and the front drains are blocked, then it would leak at the front. Usually the careful use of compressed air applied to the drains underneath the vehicle will cure things. I have also used a flexible speedo cable that I had laying around. It seems that things grow in those drains, turn into muck and plug up.

Rarely, the pan that collects the water will itself have a faulty seal, or the hose connection where it meets the pan will come off. Again, those are really rare problems and the least likely.

Here I am talking about vehicles in general. the X may have different issues. I don't think I was ever involved with a leaking X.