hello, and welcome to the forum!!

If you have water draining from the waste pipe while on filter mode, it is very likely that the multiport was put back together backwards, and it needs to be turned around. If that's the case, then just plugging the waste line won't be enough to make the filter run correctly, because the water isn't going where it's supposed to go in the other modes, either, as you can see when you turned the filter back on and blew all the dirt back into the pool. Also, when you change settings with the handle, are you making sure the pump is off, and only turning it clockwise?