Hi AWWaddell,
We’re sorry for the inconvenience caused by it.
Firstly, as you mentioned you can’t find the items in recycle folder, did you check in Second-stage recycle bin? If no, please check and restore the items if present in it.
If any of the item is present in any stage of recycle bin, we can also check the user who deleted it (under Deleted by column).
To narrow down the problem, can you please check and provide the following:
- Is the problem happens with specific SharePoint List or all the Lists?
- How often the problem occurs?
- Check whether the problem happens to List present in other sites?
- Does the all the items in the List are disappearing?
In addition, we would like to convey that items in the SharePoint List doesn’t disappear manually and as a test, can you change the permission of the members to View (so that they can’t delete any items) and check whether this problem occurs or not.
Lastly you can refer to these article: Configure audit settings for a site collection
Refer this article to check user activities in SharePoint Online and Audit events on list items are not available via Security and Compliance center. We suggest you add your and provide feedback to vote
Support audit events on List items (Office 365 Security & Compliance UserVoice) as related team can take into consideration.
Regards,
Chitrahaas