A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Hi Adam(S),
May I suggest using Internet Explorer?
Copying the content from Excel and pasting it into the existing list does work in SharePoint online.
Since you mentioned, you are using SharePoint 2019, this functionally may differ from SharePoint online. In this case, I’ll suggest you post in SharePoint Server 2019 forum to confirm whether it works in 2019 version of SharePoint or not.
The reason I ask you to post a new thread is that in Answers forum, we deal with the issues/queries related to SharePoint online and we have limited resources and very little knowledge about SharePoint 2019 environment and in SharePoint server 2019 forum, you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction.
We appreciate your understanding.
Best Regards,
Neha