File import problem "Could not get posted H5P."
When importing an h5p file from another site I get an error message "Could not get posted H5P."
I suspect this may be to do with php upload limits as this is a new Wordpress installation on a new vps installation - but I've increased the php upload imits to 5M, which is beyond the 2.8M size of the file I'm trying to upoad and the initial error message about this issue has also gone.
However, a smaller file of 0.5M has uploaded without problem.
Any ideas?