Can´t change angle for multicam in FCP7 ?

Hi there.

So I have made loads of hours of multicam videos in FCP7 on separate harddrives, and now I have transferred all material to a major 20TB caldigit thunderbolt 2 storage system, and when I open up the project from that new storage it displays everything and plays back nicely, but when I try to change the angle of the clip it gives me a warning " Operation not allowed" ???

Is it something with the read & write options of the disk? I have put them to read and write for all users.

Any help much appreciated-

Adam