Why the lead count does not match your file, why imported leads cannot be called, and where to find the rows that did not make it.
Start with the upload banner
Every import reports on itself. While it runs you get Processing leads... N processed so far, and when it finishes the banner says what happened.
The completion banner. When rows merged into existing leads it reads N leads added, M duplicates merged instead.
If any rows were rejected outright, a Download N failed link appears on the right of the same banner. It returns only those rows, with their original columns, so you can fix them and upload again.
The banner clears itself after 15 seconds. If rows failed, download them before it goes. There is no history of past uploads, so once the banner has gone the only way to get that list back is to run the import again.
If nothing at all could be created you get an error instead:
No leads were created. The data may be invalid.
That almost always means the phone, email and LinkedIn columns were all left on Ignore column, so no row had anything to identify a person by.
Fewer leads appeared than rows in the file
This is usually correct behaviour rather than a fault. Lead Hero merges duplicates on import instead of creating a second copy.
A row is treated as the same person as an existing lead if any of these match:
any phone number (primary, secondary or reply)
the email address
the LinkedIn URL
Comparison ignores capitals and surrounding spaces. Matching a lead's secondary phone against your file's primary phone still counts as a match.
So a file of 100 rows where 30 of those people are already in the same workspace imports as 70 added, 30 merged. The banner says exactly that, and the total is right even though the added count is not 100.
Two things follow from this that surprise people:
Duplicates inside one file merge too. Two rows for the same person become one lead.
Matching is per workspace, and that is the usual reason a merge does not happen. Leads are only compared against leads in the same workspace. An import that lands somewhere else creates a second copy of a person you already have, without warning. If you got duplicates you did not expect, this is almost always why. Pick the destination folder on the upload screen so the import lands in the workspace that folder belongs to, rather than leaving it to a default.
If the numbers still do not add up, check in this order: the row count on the Map columns step against your file, then the Download N failed list, then the folder and workspace you imported into, then any filter still active on the Leads table.
Imported leads cannot be called
Open one of them. If the phone column shows n/a, no phone reached Lead Hero, and the cause is nearly always the mapping rather than the file.
Set the phone column to Primary Phone rather than leaving it on Ignore column. Lead Hero only auto-matches headers it recognises, and a column headed just Mobile is not one of them.
Headers that auto-match to the phone field are Phone, Phone Number, Primary Phone, Primary Number, Number, Mobile Number, Mobile Phone, Direct Dial and Company Phone. Anything else needs setting by hand, once. Lead Hero saves the mapping against your organization, so the next file with the same headers arrives correctly matched for everyone on the team.
To fix leads that are already in:
A handful: open each lead and add the number.
A lot: re-upload the same file with the phone column mapped correctly. The rows will merge into the existing leads rather than duplicate them, as long as the email or LinkedIn URL matches.
No numbers to hand: send them for enrichment instead.
Columns landed under the wrong field
Two columns cannot share one target field. If you map a second column to a field that is already taken, the dropdown shows which header currently owns it, so check there before assuming the data vanished.
Company Description never auto-matches. Whatever you head that column, it arrives on Ignore column and has to be set by hand. Other fields have several accepted headers; this one has none that work.
If a column has no home in Lead Hero, use Add new custom field at the bottom of the dropdown rather than forcing it into an unrelated field. Custom fields are saved for the organization and appear on the next import.
The file will not upload at all
Lead Hero accepts .csv and .xlsx only. Anything else is refused with Please upload a CSV or XLSX file.
If the file is the right type and still will not read, the usual causes are a missing header row or a second header row partway down.
Delete trailing blank rows before you upload. A completely empty row is not skipped. It creates a lead with no name, no company and no number, which then sits in your list looking like a data problem. They are easy to spot after the fact by sorting on the name column, and easier still to avoid.
What to send support
Include the organization, the workspace, the row count in your file, the count Lead Hero detected on the Map columns step, the mapping choices you made, and the exact banner text.
Attach the Download N failed file if you still have it, or a small synthetic file that reproduces the problem. Do not send a real lead list unless support asks for one through a secure channel.
Next steps
Upload leads by CSV: the headers that auto-match, and the mapping step
Enrich leads with phone data: finding numbers for leads that arrived without one
Manage organizations, workspaces, and members: which workspace you are importing into