Dear KPete,
Good day! Thank you for posting in Microsoft Community. We are happy to help you.
Please make sure that “Require documents to be checked out before they can be edited?” is turned off in Versioning Settings.
May I know If you have a document library with required fields? Uploading multiple files to library with required fields is going to cause them to be “checked out” to the person who uploaded them.
If we upload a single file to a document library with required fields, we will be prompted to fill out those fields in a form. However, if you upload multiple files at once SharePoint will take them all quietly but with a serious catch: it puts them in a “checked out” state.
If you have a Content Type with required fields set for the library, you may turn off or edit the required fields for the Content Type to check the outcome. For reference: Change a content type for a list or library (microsoft.com)
Please share your results with us. Thank you for cooperation.
Sincerely,
Igor | Microsoft Community Moderator
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