Display Messages checkbox missing from Admin Panel
The admin panel normally has a checkbox to show log messages set with function \TYPO3\CMS\Core\TimeTracker\TimeTracker->setTSlogMessage. Since TYPO3 version 8.7 this checkbox seems to have been accidentally skipped during the refactoring of class \TYPO3\CMS\Frontend\View\AdminPanelView->getTSDebugModule.
This makes it impossible to show TS log messages in the admin panel in TYPO3 versions 8.7 and above. Currently the only way to display TS log messages is to generally activate them with TSConfig (admPanel.tsdebug.displayMessages = 1). TYPO3 7.6 still has the checkbox.
The functionality is still there. The HTML for the checkbox just needs to be added in function getTSDebugModule (see screenshots before/after) and according patch.