When editing a "ToDo" (work) recordtype i am unable to populate data on the "description" (agf__Details__c) field. It is visible on the UI lightning record page and is added to a page layout, however when clicking edit on the record, the field is no longer visible. (I have also checked FLS settings)
This issue could be related to the Record Type having a different layout, and that layout may not include the field or might have specific field visibility rules that hide it during editing.
I would suggest to check Record Type Layout, ensure that the agf__Details__c field is included in the page layout for the ToDo(Work) record type.