I am experiencing what many users have posted in previous years, albeit I am using the latest Excel.
The issue is a file stored on the MS Cloud Sharepoint site with 30 or more checkboxes per WorkSheet will hang and require and end task to release it. This happens after about 2 minutes of editing, be it filling in cells with text or checking boxes.
There is no code behind the check boxes, perhaps that's an ignorant omission on my part.
Is there a known fix for this? Other than replacing the check boxes with validation lists.