Why sink organizers don't fit

A molded organizer has to be made before anyone knows where it's going, so it's drawn against a basin somewhere in the middle of the range — a plausible width, a moderate corner curve, a drain near the center. Sinks near that middle do fine.

Yours is probably not near the middle. Rim shapes differ between makers, corners run from nearly square to generously rounded, and drains sit centered, offset, or pushed to the back depending on how the plumbing was routed. None of that is unusual. It's just not the average the mold was cut for.

It rocks, because a flat footprint sits on a rim that curves away from it, bridging two contact points with air under the third.

It holds water, because the drainage holes were placed relative to an assumed drain rather than yours, so water runs to a corner and stays.

It hangs over the edge, or stops short of it, because the piece is one of three sizes and your sink is not one of three sizes.

None of those are hard problems once the shape is known. They are only hard when the shape has to be guessed in a factory months in advance.

SinkSpanner scans the sink you actually have and draws the piece from that — the rim's real curve, your drain's real position. It's the same object, made in the other order.