Some reports show a group label once, leaving the following rows visually blank until the next group begins. A query can repeat that label on detail rows, but it needs a reliable record order and a clear boundary. Otherwise a convenient cleanup step can assign the wrong group to valid data.

Preserve the original report. In a small copy, include a label for Room A, two detail rows beneath it, a Room B label and one more detail row. Also include a leading unlabeled detail row. Decide which rows genuinely inherit a label and which require clarification from the source.

Determine what the blank-looking values contain

Power Query Fill Down propagates a previous value into null cells below it until a new value appears. Select the label column, right-click and choose Fill, Down. Empty text is different from null: Microsoft's filling guide describes replacing empty cells with null first, using Transform, Replace Values, a blank Value to find and null as Replace with.

Do that conversion only where an empty field means an omitted repeated label. Spaces or other characters need their own inspection; do not assume every cell that looks empty has the same content or meaning. A deliberately blank category must not become an inherited answer by accident.

Test the transition between groups

Inspect the first and last detail row assigned to Room A and the first one assigned to Room B. The label must change at the intended boundary. Then inspect the leading unlabeled row: without a confirmed preceding label, do not invent its room merely to eliminate a missing value.

Consider whether separator rows, subtotals or concatenated reports introduce boundaries that are not represented by a new label. Filling across one of those boundaries may produce a complete-looking but misleading result. Correct the structure or isolate the relevant groups before propagating values.

Reconcile a few completed records with their positions in the untouched report, including a boundary case. Keep the inherited label separate from any evidence that directly identifies a record. If an export's layout changes later, repeat the boundary check before trusting the filled column in a summary.

Sources: Microsoft: filling column values; Microsoft: Table.FillDown.