Store Dataset useing enhanced matadata format problem

When i try the "Store dataset using enhanced Metadata format" preview option,  i have one pbix which takes 30 seconds to open with the current format and 2minutes and 30 seconds with the new format.

Forcing me to revert back to the current format.

Furthermore the model becomles useless because it keeps taking 2minutes and 30 seconds : i have to restore e aprevious version.

Anyone having encountered the same issue?$

Thanks

Jmdh