Yes, Google Merchant Center has a steep learning curve and one that is unforgiving. Making a mistake can mean getting suspended or not. So with such a high risk you should definitely study up first or hire someone who specializes in the field.
What you describe can mean a lot of things.
For example, it can mean missing product identifiers, brand, gtin, mpn.
Make sure if you have a barcode on the products, that you submit brand and gtin. If not you must set the products as custom and remove brand and gtin.