Dear Chase,
Greetings! Thank you for posting in the Microsoft forum.
Based on your post, I tried to replicate the behavior, when I clicked Show all the items appear normally.
We understand you are using modern experience in your list, could you please try switching to classic experience to check if you experience the same behavior? To switch, click Return to classic SharePoint at the bottom-left corner of the page. Once in classic view, see if the items appear without any issue.
Also, the Group by view is limited to showing the 30 items only, upon clicking “Show all” it shows all the items and will autoload when scrolling down the list.
Further, try accessing the affected list in a different browser or open the same browser in InPrivate mode to rule out the browser issue. I read this post where customers are discussing a similar scenario and some customers confirmed opening the browser in InPrivate mode allowed them to view all the items after clicking “Show all”.
Besides, please check if you see similar behavior with another list.
Let me know the status. Stay safe and stay healthy.
Sincerely,
Neha Singh | Microsoft Community Moderator
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