Three equal groups contain one item each. Each share is one third, but showing one decimal place produces 33.3 percent three times, or 99.9 percent in total. That small difference can be ordinary rounding rather than a missing record.
Ask the AI to provide the source counts, denominator and unrounded calculation. Verify those independently with a calculator or spreadsheet. If the counts are one, one and one, the total must be three before any percentage presentation is considered.
Do not accept an unexplained fourth category called other merely because it makes a chart reach one hundred. A presentation adjustment should not invent underlying observations. Equally, a large discrepancy should not be waved away as rounding without arithmetic.
Choose the required precision and, where necessary, explain that displayed percentages may not sum exactly because of rounding. If a publication requires an adjusted total, use a documented allocation rule and preserve the original counts. The AI can help format the explanation, but the calculation and the editorial choice should remain visible and reproducible.