Blank screen on the iPad app when opening my saved *.mscz file

I have been learning Musescore this past couple of weeks.
I have scanned a pdf into Musescore4 app on my mac; transposed to Tenor sax; saved the *.mscz file; edited it a lot to make it right; and exported out MP3 and play that on my ipad.
Quite a learning curve. :)

I have also saved this *.mscz file to https://musescore.com/my-scores
All great so far.
I understand there isn't a full iPad app but I was able to download a Musescore app.

1) Am I right in thinking this is just to play back and not edit?

I was able to log in on the iPad app and I can see my 4 page *.mscz file but when I opened it, all I get is a page with no sheet music on.
Yet when I log onto the online version on my mac, i can open it there.

2) Am I doing something wrong?or have i misunderstood something along the way?

I have deleted my score, and reuploaded that (and 3 others) all have the same issue

Thanks in advance