This might be an obvious one but I can't work it out - I thought I was digitising in HD and was using the M100 HD compressor but when I drop clips back into a bin and look at the frame size is 720 by 576 yet the Compressor was Media 100 HD and Data Rate is Uncompressed.
I don't get it - I thought the frame size should be 1080 - or am I wrong?
The Media 100 HD codec can be both 720*576 or 1920*1080 (in fact it is resolution independant outside the Media 100 application). If you tried acquiring HD footage you most likely did not set your "Video Input" preference to HD. In this window you both can set your source standard (the standard of the incoming signal) and the Media standard (the format you want to acquire to). E.g. you could take in HD 1080 footage (source standard), and downconvert it to SD (Media standard) on acquiring. Most likely this is what happened on your project.