Paste buttons won't be shown under certain circumstances.
we use the current stable release 8.2.3 and the core buttons for pasting clipboard records won't be shown under certain circumstances.
Further debugging leads to the conclusion, when there are allowedGridTypes in a column defined and the clipboard record is no gridelement record clipboard record will be not allowed to insert the clipboard record.
We solve the problem with this code in Classes\Hooks\PageRenderer.php:
top.clipBoardElementTxGridelementsBackendLayout = '" . (($clipBoardElementData['CType'] == 'gridelements_pi1') ? $clipBoardElementData['tx_gridelements_backend_layout'] : '') . "';
Thanks for investigating the problem and releasing a bugfix in the next version.
PS: Maybe the bug https://forge.typo3.org/issues/86529 has the same reason.