Microsoft BOOKINGS not importing contacts

Question

Hello,

in the microsoft bookings, we would like to import database of our clients to the customer section. We are using the correct format of CSV and even created excel generating data according to outlook template for contacts (this article https://support.microsoft.com/en-us/office/create-or-edit-csv-files-to-import-into-outlook-4518d70d-8fe9-46ad-94fa-1494247193c7 ).

But we are not able to import more than several contacts into bookings. We have about 4000 of clients to import. So in bigger amount the csv is denied and bokings says "Something went wrong.

Is there any chance of importing bigger amounts of data in?

Thanks!

Radek