Endnote Ipad attachment deletion

I have 8500 references and most have PDFs.  the cache will fill very quickly.  I find the IOS EndNote stops downloading references at about 500 references. 

Why does it stop downloading?

Is there a way to download the all the references, which does not take very much space, but leave the attachments to download as needed?

My iPhone has 256GB, which will easily hold all my attachments according to the statistics of my library.  Can override the 100MB limit and download all, to remain on the phone offline?  Thanks

RPP