OK, this is a little complicated to understand. In the sample business you provided, the entries in your Suspense account for the blank lines show for only one reason. You do not have an account selected for the line item of the receipt. (I know, that is a totally different transaction.) But, if the receipt was intended to be against the sales invoice, you should have selected Accounts receivable >> customer1. Selection of the unnumbered sales invoice would be optional. Because the receipt was incompletely filled out, it was thrown into Suspense, making the balance of Suspense non-zero.
Once the balance of Suspense is something besides zero, the account and its balance are displayed on the balance sheet. At that point, you can drill down to see what is in the account. And you see all the blank line items because each is entered separately in the general ledger. Since you never changed them from their default posting to Suspense, there they are. In other words, you see the blank lines from the sales invoice because of your error on the receipt.
If you could see the balance for Suspense when it was zero, you would have seen all these blank line items, but you couldn’t, so you didn’t.
What is the lesson? Don’t use blank line items for spacing or layout purposes in an accounting program. They are not just line spaces like in a word processing program. They are actually accounting entries. Do they do any harm? No. But they make it harder to find real problems.
Now, turn back to your real business. The fact you could drill down to see the list that includes the blank lines means your Suspense balance was not zero. So you had incomplete or erroneous transactions waiting to be fixed. There should never be anything in Suspense. Drill down on that account, sort the Debit or Credit column to group all the non-zero amounts together and fix those transactions. Then repeat for the other column. See this Guide: https://www.manager.io/guides/7106.