Hi there, @TP41.

I acknowledge your concern about importing products and services in QuickBooks Online (QBO) Advanced. For a company like yours, it's important to be able to import bulk entries at a time. 

Importing files into QuickBooks varies according to the file size and the allowable number of rows to be imported. QuickBooks has also been rolling out new updates to help businesses better manage their products, services, and inventory by importing them into the application. This update includes new features and allows users to import up to 150 rows at a time. Otherwise, it is best to split the data into multiple smaller files.

To verify, let's check which version your account is using to determine why you are only able to import fewer rows. Here's how:

1. Go to the Gear icon and select Import Data.
2. Select Products and Services. For the new version, you'll see a Batch-import screen with a spreadsheet layout. Otherwise, you'll see an option to upload a CSV, Excel file, or Google Sheet.

Once verified, you can upload the file by following the steps designated according to what version you are using from this article: Import products and services into QuickBooks Online.

Since there are limitations to it, I suggest splitting up your file into multiple, smaller ones. Or, you can utilize the Spreadsheet Sync feature in QuickBooks Online Advanced. This option allows users to add or edit large batches of data in Excel. To do that, you can follow the steps below:

1. Go back to the Import Data section.
2. Select Product and Services in the Import field.
3. Choose Import from Excel using Spreadsheet Sync and click Next.
   
4. Press Next again and follow the onscreen instructions to continue.
   

See the types of record templates in Spreadsheet Sync to learn how you can add or edit a list, and which transaction template can be used: Import data using Spreadsheet Sync in QuickBooks Online Advanced or Accountant.

After that, we can run the Products and Services List report to double-check if the application successfully imported all your items.

Let me know if you have additional questions about managing your file or inventory in QuickBooks, @TP41. The Community always has your back. Take care!