With org-mode 9.4, if you have a repeated task like this: * TODO My weekly task SCHEDULED: <2020-10-14 Wed +1w> In daily agenda, if you mark the task done, which will cause the above to change into: * TODO My weekly task SCHEDULED: <2020-10-21 Wed +1w> :PROPERTIES: :LAST_REPEAT: [2020-10-14 Wed 11:45] :END: :LOGBOOK: - State "DONE" from "TODO" [2020-10-14 Wed 11:45] :END: But then if you run "org-agenda-undo" immediately in the agenda buffer, the task did not revert back to the original, instead, only the "LOGBOOK" part is gone, so it becomes this: * TODO My weekly task SCHEDULED: <2020-10-21 Wed +1w> :PROPERTIES: :LAST_REPEAT: [2020-10-14 Wed 11:45] :END: I don't think that's what people would expect from "org-agenda-undo", so it seems a bug to me. This bug is also in orgmode 6.3.7, so likely has been there for a long time. Thanks for looking into this. Warren