Adobe DC Copy Paste Full Pages stops working

I am compiling pages from different pdfs into one pdf as a data source document. I will use the pages panel on the left hand side to select a page ctrl + C (or right click- copy), then go to my data source document and paste that page in the order I need.

After about 10-15 pages, the copy function stops working. I will highlight a single page, right click - copy and nothing happens (typically this will produce a symbol indicating the page was copied). Ctrl + C doesn't work either. It's as if Adobe's clipboard is full and cannot take any more information (though I know of no way to clear a "clipboard" or "cache" or if one even exists in Adobe Acrobat DC).

If I close Adobe Acrobat DC and re-open, I can once more copy and past full pages. Also, if I split-screen I can drag pages from one pdf to my data source document and it will automatically copy. But again, I cannot use ctrl + C or right click + copy.

I'm complining pages from 8 pdfs (some containing thousands of pages) and closing/reopening them is quite time consuming. Please help any way you can and thank you.