Issue pasting numerical values into SharePoint list

Hi all, would really appreciate some help here. As of a few days ago, we've started to experience an issue when it comes to copying and pasting rows over from an Excel document into our SharePoint lists. This issue started off affecting just one of our lists but now it's starting to affect almost all of them - jeopardizing our processes which we've had set up for years with no issues.

Where there's a mandatory numerical value, it's stating that the field doesn't have a value, even though there's one provided as you can see on the attachment below. For any fields where numerical values are not mandatory, it's simply removing the value altogether. So we can manually go into a row where there's a mandatory requirement on a numerical field and press enter on the value, which then inserts the row fine but then where it's not mandatory it's just wiped the values completely. Our lists consist of many numerical fields and we're pasting in hundreds of records a day.

Again any help is much appreciated

Thanks