The Plugins tab lists again

Both plugin lists rendered as nothing after the ng-bootstrap upgrade removed the accordion component the page used, which Angular reports as neither an error nor a warning. Migrated to the directive accordion, with the upgrade button moved out of the header button it was illegally nested inside.

Settings → Plugins rendered both of its lists as nothing at all, which reads as "plugins have stopped working" — the one thing this fork exists to avoid being true.

It was markup, not compatibility. <ngb-accordion> and <ngb-panel> were removed in ng-bootstrap 15 and this tree is on 21; an unknown element is not an error in Angular, so there was no exception, no console warning and no failed build. The page simply resolved to nothing. Migrated to the directive accordion the Link Tooltip page already uses.

• Plugins themselves were never affected, and that was measured rather than assumed: 21 load, including all three third-party ones, their config keys are present in the store, and the repaired Installed list shows 19 entries.
• The upgrade button is now a sibling of the toggle rather than a child. The old component API rendered the panel title inside the header button, so a plugin with an upgrade available produced a button nested in a button — invalid, and swallowed in some browsers.
• The stylesheet had been targeting .card-header > button, which is ng-bootstrap 4's markup. Nothing has emitted that element for several majors, so it had been styling nothing the whole time.
• A search of the tree found these two tags in this component and nowhere else, so the same fault is not hiding on another page.

• Verified in a live window — 144 available, 19 installed, zero of either removed tag, zero nested buttons — but installing or uninstalling a plugin from the repaired page has not been exercised end to end.