After applying the 7.10.0 update and using the new Registrar TLD Sync tool with ResellerClub (NetEarthOne, Resell.biz, Stargate). You may observe that that the cost prices imported are showing an amount converted into a different currency.

This occurs when the ResellerClub account's parentsellingcyrrencysymbol and sellingcurrencysymbol settings are different.

Please apply the 7.10.1 Maintenance Release via the Utilities > Update WHMCS page.

A hotfix has been created for 7.10.0 only which will resolve the cause of this error:

https://whmcs.community/files/file/129-core-14497-resellerclub-tld-importsync-currency-issue/