KNIME 5.9 Preview - Parquet Nodes disappearing

It seems that in the latest KNIME 5.9 Preview (nightly build) the Parquet Reader nodes simply disappear and are not present when opening a workflow featuring them. Also they are not being prompted to be installed.

KNIME Community Hub

Try to load this workflow and see the parquet reader not being there on the left side:

KNIME Community Hub

Maybe I have to install all of the nightly build again since there seem to be some preview KNIME 5.10 items still in play.