TYPO3 should tell the reason why translation in mixed mode is not possible
TYPO3 supports both "connected" and "free" mode for the translation of page content.
If for some reason it happens, that the page translation is in mixed mode (both connected and free mode records exist for this translation), the "Translate" button is still clickable but the wizard won't show a clickable option.
In such a case TYPO3 should show a message in the wizard overlay that explains, why using the translation wizard is not possible in mixed mode.
-> See screenshot for the current behaviour. An empty wizard will open with no option to go further, which looks confusing to the editor.