Init the CUSTOM preset not just with the capabilities, but also with the "temporary" status of the previously selected one.

src/ui/ui.js

@@ -425,7 +425,8 @@ var UI = (() => {
           if (isTemp) {
             row.perms.temp = target.checked;
           } else {
-            let temp = preset.parentNode.querySelector("input.temp").checked;
+            let temp = row.perms.temp;
+            tempToggle.checked = temp;
             let perms = row._customPerms ||
               (row._customPerms = new Permissions(new Set(row.perms.capabilities), temp));
             row.perms = perms;