copy paste a 512 row pattern, go to a 64 row pattern and paste. now paste again. this re-pasting will change the current pattern row-amount from 64 to the clipboard amount i.e. 512.
a simple context menu entry would be to paste continuously or paste with pattern resize
found some solutions to this instead (create clone of current pattern and switch current pattern sequence to new, cloned pattern). so that’s solved for me, at least.