There seems to be a bug with memos not showing consistently in the sidebar of the document browser. Sporadically, after opening a document with an existing memo tied to some text, and with the show sidebar option enabled (before opening), the memo does not display in the righthand sidebar. Clicking the memo icon on the left sidebar also does not seem to trigger anything. The only solution I've found is to disable and re-enable the show sidebar option in the menu bar.
Version: MAXQDA 2020
System: Mac OS X 10.14 (Mojave)