I just upgraded to 2020.2.6 and noticed that if you sort/filter the all nodes tree by any custom property that contains the ampersand (&) symbol, the nodes will not show up. I test this in another instance to verify. The arrow symbol will flicker when you click on it and then now show any nodes. Other symbols are fine such as hyphens(dashes), parentheses, and asterisks. I believe underscores may be fine also.