ios12 how to open pptx in keynote

Hi 😉

IPad Pro 10,5

ios12

After upgrade to ios 12 I cannot open pptx in keynotes on iPad. Everytime I get info about invalid format.

Tried: opening from files, opening from keynote, sending pptx via airdrop. Nothing works, but did work before upgrade.

Any hints?

reg, Aga