You can consider removing some columns you don't need to be displayed to export the customer list to Excel successfully. Let me guide you through the process.
Before we start, please know that there are size limits when exporting data to Excel. Here are the following:
Maximum of 1024 columns displayed
Maximum 400k cells with data
Maximum 10MB worth of data
If your data exceed the size limits, let's eliminate some columns that you don't need. Here's how:
If you're exporting the data from the Customer page, please follow the steps below:
Click Sales from the left panel, then select Customers.
On the page, click the Gear icon.
Select a column that you don't need to be displayed.
Then, click the export icon to export the data to Excel.
If you're exporting it from the report, feel free to go along with the steps below:
Click Reports from the left panel, then search for Customer Contact List.
In the report, click the Gear icon, then remove the unnecessary columns.
Select the export drop-down, and choose Export to Excel.