There seems to be a bug in the MEP objects.
I don't have that particular object (probably because I have the AUS template?), but my default basin has the same problem.
All is good when first opened.
But if you change the tap style one of the connections disappears.
Or maybe they are doubling up?
Even changing back to the original tap does not reset it.
The way to fix it (until you change the tap again) is to swap the basin style for another and then set it back.
I am just setting up 24 and looking at this MEP stuff.
I must say I am not impressed so far.
The system itself looks good and works pretty well (mostly).
But many of these MEP objects are buggy or have a lack of control.
I won't go into details here but maybe I will compile my list of problems and make a new post some time in the future.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10