The scenario
When you share a dashboard with your clients through the Client Portal, the company slicer filters each report down to the viewer's own company. That match is made between the portal user's email and their contact record in your PSA.
If a portal user's email has no matching contact in your PSA — a personal address, a typo, or a contact that hasn't been added yet — their company can't be resolved.
What we'd like
For dashboards exposed in the Client Portal, when the viewer's company can't be resolved, the report should show nothing by default, together with a clear message telling the user to contact their administrator.
"We can't identify you" should never resolve to "show more."
Current workaround
Both steps are worth doing today on any dashboard you share with clients:
Enable Strict Mode on the company slicer of that dashboard.
Before granting a portal user access, confirm their email exists as a contact under the correct company in your PSA. That match is what drives the company filter.
Why it matters
Your clients only ever see their own data — that's the entire premise of a client-facing report. Making that guarantee independent of per-report configuration removes a class of setup mistakes, which matters most as portal users get added over time by different people.