This is not a bug. It is a subtle design failure that has been hiding in plain sight for decades, and the fact that a user had to record their screen to prove the math was changing proves how deeply we have learned to mistrust our own eyes when software behaves inconsistently.
The user, lsharris, noticed something genuinely strange: highlighting the same two cells produced a different sum depending on whether they dragged the mouse upward or downward. That should never happen. Spreadsheets are supposed to be deterministic, the same input yields the same output, every time. Yet here, the direction of a drag gesture changed the result. This is not a complaint about rounding errors; it is a documented observation that the tool failed a basic test of transparency. The user is right to ask whether this is a feature or an issue, and the honest answer is that it is a feature that was never clearly explained, which makes it an issue in practice.
What is happening is that legacy spreadsheet applications often include hidden logic that expands or shifts the selection range based on how you drag. Some interpret an upward motion as an attempt to "extend" a selection differently than a downward motion, especially when there are merged cells, hidden rows, or array formulas in the vicinity. The status-bar sum then reflects a different range than what the user thought they highlighted. The tool is making a guess about intent, and it is guessing wrong. For a user who just wants a quick sum of visible cells, this feels like the software is gaslighting them. The practical takeaway is that most spreadsheet applications lack a simple, visible indicator of exactly which cells are being included in that status-bar calculation. Users should not need to record their screen to debug a sum.
This is exactly the kind of friction that an AI-native spreadsheet should eliminate. Instead of silently applying hidden heuristics that change results based on gesture direction, a modern tool can surface the logic in plain language. Imagine highlighting a range and seeing a small label that reads "Sum of 4 visible cells: 127.50" or "Excluding hidden row 12." That is not futuristic; it is basic feedback. The fact that this does not exist in most tools today is not a technical limitation, it is a design choice that prioritizes legacy behavior over user understanding. The user's confusion is not their fault. It is a signal that the interface has failed to communicate its own rules. The next generation of spreadsheets should treat every user interaction as an opportunity to confirm intent, not to guess at it.