Four explanations, in the order worth checking.
The period has no activity in it
Month to date early in a month is a few days. A quarter not yet started contains nothing.
This is the most common reason and the quickest to rule out by widening the range.
A filter is still applied
Filters persist between visits. A filter set on a previous occasion — a customer, a job type, a status — remains until it is cleared, and a combination that matches nothing produces an empty result.
Clearing all filters and reapplying one at a time identifies which.
The report draws on a source that is not connected
A report built from accounting data has nothing to show where only bank data is connected, and the reverse.
Sources shows what each connected system provides.
The figures are held back
Where the underlying data is not complete enough to support a figure, it is withheld rather than presented with a caveat — see how confident a number is.
This is deliberate, and it resolves as the underlying records fill in.
A new workspace
A workspace connected recently is still receiving history. Bank and accounting connections deliver several months on the first sync, and reports covering earlier periods fill in as that arrives.
If the period, filters and sources are all as expected
Tell us the report, the period and the filters — see getting help.